 Welcome to Computer Science E1 Lecture 7. This is all about security. So before we dive right into talking about security, I'm going to steal away the focus from David's laptop and just talk a little bit about the most recent problem set. So problem set 5, multimedia, as you know, you'll need to load Photoshop either on your computer or come use Photoshop on one of the campus machines in a lab. And we provided a very convenient or what we thought was a very convenient link to a trial version of Adobe Photoshop CS3. Unfortunately, this link, although this link works, the trial does not work. And the reason seems to be that Adobe has just moved to the new version of Photoshop CS4 and we're in this sort of transition period where they don't yet have the CS4 trial version available and they've expired the CS3 version. So in this limo period, so what does that mean? It doesn't mean that we're going to cancel the problem set or anything like that. You can't get out of it that easily, unfortunately. You can actually download Photoshop as part of FAS keyed program and I'll explain a little bit more about that in a second from the FAS download site. And don't worry about too many of the details. You'll get an email from John pretty soon, hopefully in the next couple of days for all of the details that you need. You would basically just go to, let's see, it's downloads.fas.harvard.edu and you'll have to enter in your Harvard ID and PIN to get access to this downloads page. From here you will download Photoshop and you'll find it, they have a version for both Mac and PC but you'll notice that there is very unfortunate requirement for using Photoshop on your own personal computer and that is that you have to use what's called a keyed version. What this means is that in order for you to load Photoshop and use it on your computer you must be connected to Harvard's network so that Photoshop can communicate with a pool of licensing servers that we have here so that it will know that someone is using Photoshop through FAS. So what this means essentially is that not only will you download Photoshop but you will have to download the VPN client which allows you to connect to Harvard's network and also the key server which is also on the same page, you'll notice it is here, key server. So that's three things, Photoshop itself, the key server and the VPN. You will have to have an FAS account in order to VPN in and it gets, as you can tell, there's a lot of steps involved but it will let you use Photoshop on your home computer. The alternative is that you can come to one of the labs on campus, you have access to it either the Church Street lab or maybe one of the Mac labs in the Science Center for example they all have Photoshop installed on there. So rather than worrying about VPNing in using key software through the FAS download or having to get an FAS account you can just use one of those computers. So there are options still available in order to get this problem set done but like I said forthcoming details from John. Over to you. So we thought we would try a little good cop, bad cop tonight. So there's no lecture more engaging than one in which we scare you it seems based on many, many times of trying this and so what we thought we'd do is my role will be to point out and explain all of the bad stuff that can happen to you online all the bad stuff that can happen to your information, to your identity, to your money and so forth and Dan will sweep in just after you've been terrified hopefully and point out technological or sociological solutions to those problems and so the goal today will be partly about understanding technologically what are security threats today, what are threats to privacy and such but also in more real terms what you can actually do to mitigate or deal with those kinds of threats and you'll find that much or all of tonight's content is in fact very real. So let's get off with a bit of an example. This is an example of what's called a packet sniffer. So we know from our internet lectures that data goes back and forth not only across wires but across the air so to speak wirelessly using that protocol called 80211B or G. So in this room you have one, two, three, four, five, six access points wireless access points with those antennas around the room. There's all that much going on in this room right now according to my laptop so I'm connected to one of those access points and what you see flowing up on this screen are all the packets going back and forth in this room and what that suggests is that you and you who are on your laptops here if you're sitting there browsing Facebook or instant messaging or sending some personal email well we know in theory exactly what you're doing because if I actually hit the save button in this program this packet sniffer not only would it watch as all this data goes back and forth I could certainly keep copies of it locally and so when you log into AOL instant messenger with your username and your password bam I've stored it on my hard drive because you did so wirelessly. So this is one of the threats that we'll talk about in just a bit tonight namely the insecurity of wireless data and what you can do to mitigate that. But first let's tie in one of our earlier lectures so we started off the course talking about hardware and one of the things that I did in years past was forensics work when I worked for the local district attorney's office one summer and our job back then was again taking media that the local mass state police had brought in hard drives flash drives even floppy disks and CDs and our goal was to find evidence on these pieces of media we our goal was to sometimes delete files that some suspect had in fact tried to or had in fact deleted but there was always a problem with this at least for some of these suspects. Let me since our projector screen here tends to get in the way let me go ahead and do things this way so on a hard drive we have so inside of a hard drive is what? Physically what's that? Okay so plates are platters more properly so platters are those like metal circles on top of which are magnetic particles and it's the alignment recall of those particles that actually dictates whether a zero is being stored or one's being stored if the particles are say north-south it means one thing or south-north it means another thing well what does it mean and we touched on this briefly in a previous lecture to delete a file well if this is one of those platters and let's just suppose for the sake of discussion that this part of the platter just happens to have a whole bunch of zeros and ones that represent some very secret file a love letter that you never want someone to see an excel spreadsheet with financial data that you never want anyone to see anything that's somehow important to you and you go ahead upon deciding you know what I really can't leave this evidence around to delete the file and so you drag it to your recycle bin or on a Mac you drag it to your trash can and most everyone in this room now knows that that's not enough right because what's really happened when you do that exactly just gets stored in the trash can or in the recycle bin but it's perfectly recoverable and typically stays there until you proactively right click or control click on the trash can and say empty trash or empty recycle bin or if you wait long enough the operating system supposed to eventually get rid of it for you as it cleans up space but suppose that you're you've taken the one and so you go ahead and right click or control click and you say empty trash or empty recycle bin now you can't recover it because if you then double click your trash or recycle bin you'll see that there's nothing there after you've clicked that particular option but what has happened physically on the hard drive when you went and actually quote unquote deleted the file yeah it's kind of hiding it in what sense do you recall recall you say okay I guess we have to give full credit for that what happens on disk yeah yeah so file allocation table so recall that there's some kind of table maintained in addition to the actual bits that comprise a file there's some kind of um table say like a not to conflate the two but the equivalent of an excel spreadsheet stored somewhere on the hard drive that has at least two columns one column is the name of a file and what did we say was in the other column conceptually where it's located right because if you can store a whole bunch of bits or bytes on a disk you can number them say this is byte number zero this is byte number one now you might be counting a long long time right if you have a 200 gigabyte hard drive that means you can count from zero to one to two to 200 billion so that's a lot of numbers but certainly computers can count that high so what happens when you actually delete a file by going to the empty recycle bin or empty trash well that table which I might just draw very simply again is a very simple table which might look like this and in this left column is the file name and in the right column is the location pardon my handwriting it's even worse on a tablet well if my file was called something like uh love dot doc and it was at location say one two three four where this just happens to be here location one two three four on disk because over here is location one dot dot dot right so I'm sort of doing this on the fly well what happens when you delete a file well all the operating system windows or macOS really do is erase that what do they not appear to be touching at all the actual bits and so when we in the DA's office wanted to try to recover data which frankly given the local criminal savvy was not all that often usually the data was still right there on the desktop we would run special software that would try to recover this allocation table that would try to recover the original location and if there was just no remnants of that row in the table so to speak well we would instead use other heuristics it turns out that microsoft word documents if you look at the bits inside of them even though there's a huge amount of variability when other people when different people make different word documents the start of a word doc is always the same in terms of its bits and the end of it is often the same jpegs as well even though photographs might look completely different there's always a common set of bits at the top that are the same for a jpeg and a common set of bits that are the same at the bottom and so we can look for these signatures so to speak and actually recover data even though the suspect or just the normal person off the street tried to delete that so what's the good thing about this I mean clearly there's a downside where if you're doing these illegal activities and you need to erase all of this data oh okay even if you want to hide your indiscretions from your significant other but there must be something that's good about this as well you're the good cop this is my stance as a good cop what is good about this right so if you accidentally delete it and let's assume for a moment that we haven't already overwritten the bits and the data that is that makes up the actual file we do have the possibility of retrieving that file so let's say that you made a couple of mistakes and first you dragged a very important file into your trash and you said oh shoot I should get it out of there and instead of taking it out you accidentally click empty trash now you might be able to in many cases recover that file however of course you shouldn't actually write any additional data to the hard drive because once you start writing more data the possibility of that same location one two three four being overwritten by new data starts to increase you know well I'm sorry I was reading what's next on the agenda oh I see sorry what was the end of okay um wow there's a flaw in our system apparently apparently okay I'm ready for the next topic are you I am no I'm sorry what was your question I didn't have a question oh so what's good about this okay well the next question though is now how do you actually get rid of data when you want to get rid of data that's not a question that's not a question well I mean that's not the question that I had what was the question you had I didn't have a question then why can't you take that question okay so let me fix this alright so this is how things work and there are upsides of this because it actually can be useful to recover data because there are these remnants on the hard drive and it's certainly good for the investigators because they can recover data when someone tried to hide that same data but the good cop question was supposed to be if this is in fact just private data whether it's financial data or medical records that are legitimately on a law abiding citizens computer for which you might have a genuinely compelling reason to want to eliminate completely that begs the question how do you go about doing that how does a normal person who has Windows who has macOS go about deleting things in a quote unquote secure way so we've already hinted at this when we were talking about it before that most of the time when you delete something you can recover it if some other condition has not happened what's that right so if you have now written data on top you should be able to recover it so how then can we be sure that the data that we erased is actually gone we would want to do what yeah right over it very good so that's exactly what we would want to do whether or not you want to just write over it with all zeros all ones any amount of writing over the data will essentially protect you from or protect the file from being read again now there are third-party utilities that you can download that will do a number of rewrites where they can either write all zeros they can write all ones or some collection of random ones and zeros and many times you are given a number of options of passes to do so for example rather than just writing all zeros once over that one particular sector that one location on hard drive you could write it seven times or 35 times and so this might take a lot longer obviously 35 times longer than one pass but if you're really truly paranoid you might want to do it however there's not really any indication that you are getting any additional safety out of 35 times versus writing over that same section of data seven times or even just one time there's still that option is there in fact one of the things to bear in mind is that even this is not a perfect solution the existence of these tools that Dan alludes to in fact one of the things we'll have you do for this next problem set that focuses on security is read an article that was written by a couple of colleagues one colleague of mine and a buddy of his at MIT a couple of years ago and the article is called Remembrance of Data Past and what these guys did and what one of them has continued to do for the past several years is buy a whole lot of hard drives off of eBay and now he's got several hundred of these things and what he's been doing over time is analyzing them and looking say for the frequency of old credit card information of financial information of health care information not for nefarious purposes but to actually put some statistics to actually how common it is for hard drives to be disposed of without someone taking these good cop measures to try to eradicate steps I mean certainly here at Harvard or UHS University Health Services there's so much data on you for instance floating around and it's often you know the IT guy who is ultimately responsible for disposing of older computers or getting rid of hard drives that maybe are too small to be kept around and the tragedy of this is that one a lot of IT people either don't know how to properly sanitize disks although fortunately the world is getting better at this or they just don't care because in fact it can take quite some time to thoroughly wipe so to speak or scrub so to speak a hard drive because if you have to write over every single bit every single byte on the disk sometimes even more than just once just to be particularly paranoid and even adhere to certain department of defense standards it can take many many hours and this is just not all that much fun so if you don't mind my stealing a bad good cop role what's an alternative perhaps to this software based approach would you think what's the most draconian what would you do if you were completely flipping out over something important behind on hard drive and you have no idea or you completely zoned out to that e1 lecture where we told you the specific software tools that exist what might you try oh I saw hand gestures so a hammer right physically break the thing is one option although as you may have seen in section sometimes it's not that easy to pop these things open interesting so certain magnets you'd have to have a really really super fancy magnet like holding it up to the fridge probably won't work but in principle yes that would work if you had access to a de magnetize or something that's really draws a lot of current a tub of acid a tub of acid so better if you don't have a magnet the tub of acid could work yeah interesting water so so putting it in water may or may not work because many hard drives are actually sealed some of them have little little holes to pressurize or depressurize the hard drive but many of them are sealed and so all you would do is ruin the electronics that are visible on one side of the hard drive however it is possible to replace that board of electronics with another board and still be able to access the data so what you want to do is essentially just destroy the platter itself it's not enough to just destroy the electronics or even the case of the hard drive because you could still have data that exists on the platters so whether or not that means unscrewing the top and taking a hammer to the platters themselves which by the way make a very satisfying crunch when you start to destroy them what a lot of people do is also just take if you have access to a machine shop just punch a huge hole using perhaps some large metal or metallic drill that can just literally go through the entire hard drive just drill a few holes and it depends on the sophistication of your tools and how much fun you want to have destroying the hard drive really but for people without tubs of acid unfortunately there do exist some other solutions so for instance probably the best or best reputed piece of software that's 100% free is called Derrick's Boot and Nuke D-Band so if you just google this so it's dban.org dban.org this really I think this is there a Macintosh version of some sort now this definitely works on PC hardware no matter what operating system you used to have on it and it does so let's say Apple Power Mac okay so it looks like it's in beta form but quite possibly could work just fine so in a nutshell what this software allows you to do is you download an ISO which is like a CD image and you need to have CD burning software typically you go ahead and burn in on a CD although there is a floppy disk version as well or a USB stick version as well and so it does assume a little bit of SAPI that one you know how to burn a CD and two you know how to boot your PC off of external media like a USB stick or putting a floppy in or CD nothing that's very hard but if you've never done it before it might be a little new and the only thing to bear in mind is that this literally is designed to wipe all of the data off of your hard drive and again it might take several hours but when you boot this software up probably following its instructions which again are going to appeal more to the geek than to the lay person just because of the nature of the software you'll get a whole bunch of options whereby you can specify how you want to wipe the hard drive do you want to just write it over with zeros do you want to write it over with random data how many times do you want to do that and then you just hit go you hit F10 or some you know keystroke you're not likely to hit by accident because it will wipe your entire hard drive on your computer but the reason I personally would recommend something like this if you do have some worries and you want to get rid of data reliably is that as you'll see in this MIT article these guys couple years ago but I'm sure it still rings true now assessed many different software products on the market at the time wiping programs scrubbing programs for which people would go to Best Buy or go online and shell out 20 bucks, 40 bucks, 50 bucks paying for software that's supposed to not just wipe the whole hard drive but just wipe certain parts of it right you don't need to wipe your whole hard drive in fact you don't want to if you actually have data on there you still care about but it would be nice if the software could just get rid of remnants of old files that you deleted but not touch current files that you don't want to delete the catch is every product they evaluated was buggy and they found traces of data that was supposed to have been wiped away but the manufacturers of the software that were charging good money for this just screwed up and so an appreciation that people make mistakes when implementing the software and that really the only true way to destroy your data is physically if not with the tub of acid you can outsource it to a company that does own a big drill this is what companies do these days or you wipe it on a software level which tends to be pretty reliable because it doesn't try to be very intelligent about it it just does everything all at once and so generally for these sorts of products you don't want to spend a lot of money on it for example D-Ban here is a great free software that will allow you to do the same thing and on the Macintosh side just because D-Ban is not quite in in production level software quality for Macintosh we do actually have built in capabilities if you have a Mac to be able to wipe a hard disk so if you just go to the disk utility which you can find in the utilities folder in applications you can select one of your many hard drives like I have here and if you click on the erase tab that's up here you can actually click on the security options you'll be presented with a list of a variety of secure erasing options so obviously the first thing is to not erase any data but you can do a zeroing out which is a one pass erase where it just writes everything with zeroes or you can do a seven pass or a 35 pass erase which basically does the same thing but seven times or 35 times and so all of this is pretty useful and if you ever sell your computer or your even a USB thumb drive we highly recommend that you use one of these methods because it is possible to recover data on very many of these things and even if you do something like format many of the a lot of the software for example Windows or macOS when you try to format a drive we'll say warning everything will be erased but it's the same exact thing as actually deleting a file it's just erasing the file allocation table and all of the bits still exist so even if you do a format you really should do an erase with zeroing out or random bits of data by one of these bits of software one of these pieces of software that David and I have been talking about just to absolutely protect yourself and just to get on the soapbox for a second do you mind clicking security options again frankly this is the way the world should be the fact that you have to go to some website download free software burn it to a CD put it in your PC like it's a mess doing this on a PC and Microsoft Windows XP and even Vista have just not made this as easy as it should be fortunately macOS has gotten to a much happier place in fact there's an option as well do you mind showing them secure empty trash whereby when you delete something proactively from the trash can on a Mac you can actually tell the OS really get rid of this securely don't just forget about it secure empty trash will like David said it will not only erase its contents from the file allocation table it will only erase its reference but it will overwrite the bits of the data itself with all zeros I think it would be in this case and just to give a little bit more information if you are going to sell your computer or if you have to erase the main hard drive the hard drive that contains your operating system or in other words the hard drive from which your computer boots you usually have to boot into a CD or a disk in order to erase it that's true on windows machines and on a Mac as well so whereas here I could go to the security options and securely erase one of my external drives I cannot actually do the same thing for my internal drive you'll notice that the security options is greyed out I would have to put in my macOS 10 disk reboot the machine and there is a disc utility in the macOS installer that lets me do the same thing but now because it's not the boot disk I can erase the main hard drive just to put on one's engineering hats why do you think that's the case, why can't you wipe the hard drive of your computer because it seems so much easier just to do it that way it really does boil down to something that simple if you are running the operating system and you kind of need the operating system because in the operating system is the software with which you need to do the wiping you can't get rid of the operating system and expect the wiping to keep working it really is as simple as that so since I'm supposed to play the bad cop here suppose that I'm a bad guy and I don't care so much about recovering data from someone's computer I just care about walking up to them in the library on campus and when they're not looking stealing their laptop what could the owner of that laptop have done in advance to decrease the probability that that laptop's data will be useful to me this is for you it's for me the good cop so I'm setting you up rather than explaining well I think this is a very good question for everybody else does it know a little bit no so what can we do I mean short of having these really stupid huge locks where we actually physically lock down a computer what we are talking about is the data itself let's say you step away from your computer for a moment we have a somewhat sophisticated hacker who wants to just come up and just copy as much personal information as they can from your computer onto their own thumb drive and then run off before you come back from your extended bathroom break what can we do yes so after so many minutes the computer locks that's true although if they have physical access and let's say they really didn't like you they could break apart your computer and grab the hard drive run off with just the hard drive and they still have your data yes encryption software you're right very good so and again this becomes somewhat specific but there are specific applications or software that you can download that allow you to encrypt certain portions or the entirety of your hard drive very much in the same way that we would use let's say HTTPS in a web form over HTTP to securely transmit information so all of the information that's on your hard drive would then be encrypted and so we would have to talk specifically then between Macs and PCs but Macs do include something built in called file vault that essentially allows this to happen however it's very very basic all it does is it encrypts everything in your home directory so that's usually all of your documents and all of your settings and your movies your pictures etc which is generally everything that you want to protect but sometimes you want to protect everything which includes all of your applications or all of the system wide settings not just the settings that apply to your specific account and there is some software on the PCs that allow you to do it and hopefully I've lab long enough for David to bring that up on his screen anyway there is there is software that exists let's see what is the name of the one on the PC there's some that are you don't know I don't use such well I mean neither do I frankly because what we've talked about before is that there is some downside to actually encrypting all of the data what is the downside of encrypting data sure it's more secure and we're protecting ourselves from hacker being able to run off with my computer and be able to look at all of the data that I have created or that I have stored what's the downside to this I'm sorry so it might take up a little bit more space but that's not really the main problem here yes right exactly you have to decrypt it to access so your computer has to do a number of steps when it's writing the data to the hard drive it has to spend the time to encrypt the data then when it's reading the data off of the hard drive it has to spend the time to decrypt the data this takes a bit of time especially on a laptop which ironically is the type of computer that you would most want to encrypt your data so and it actually is quite a noticeable hit and for a while I tried using File Vault and while it is great because it offers this additional level of protection it's just not worth or I didn't find it worth the performance penalty because now all of a sudden all of these programs that I'm using that access data take much longer to process so right so to reiterate John's comment for the cameras if the hard drive that is encrypted using File Vault or more specifically a home folder is encrypted using File Vault and the computer has died or the hard drive has died it becomes much more difficult to get all of the data off of it and it's exactly for the same sort of reason when a when the data exists in an unencrypted form not only is it easier for the bad guys to get access to it it's also much easier for us the good guys the people who actually own the data to get access to it as well so it's just very much a give and take a compromise between security and performance and convenience ease of use all of these things so certainly you have to weigh how important your data is on a computer or how important your data is on your laptop versus you know how much you want to risk slowing it down or how much you want to risk actually giving that data away so there are some better solutions perhaps to encrypting some of this data any ideas for that so rather than maybe encrypt everything what could we do instead yes so we could encrypt a specific location so maybe you have a little USB thumb drive you could store all of your most important data it's your tax information your health information all of this very personal very private data that you absolutely do not want getting outside of your hands and you could just encrypt that entire device you have a little bit less space but you're not taking the performance on all of your data you're not taking the time to encrypt your pictures which probably are not that important to encrypt you're not taking the time to encrypt all of your movies which almost certainly are not worth the time to encrypt so if you just take the time to separate out your most important data from your least important data then you can encrypt only the most important data and then spend the time actually decrypting that yes if something happens to the computer that was used to encrypt it can you still recover it yes in almost every case and usually the reason is that when you use some specific software to encrypt or decrypt something you just have to have the device that is encrypted or the hard drive or the thumb drive that is actually encrypted you have to have the software that was used to encrypt it or decrypt it you have to be installed on one computer you could have a sea of laptops that all have the same software but the way that you would decrypt it then is to have just some password for example that's usually how these things are encrypted you just have to have very secure very strong password that is used as a key of some kind to unlock and relock or encrypt and decrypt this data so by remembering your password and by having this specific software you would then be able to do it and I believe this is still up so you can see that here in file vault it's asking me to set a master password and that is exactly the reason it needs this key or this password in order to encrypt all of this data if I lose that password there's not much I can do I'll be stuck with all of these various attacks trying to crack my own password and that's another downside what happens if you forget the password to your own encrypted folder well you're quickly out of luck but assuming that you don't forget your password that's generally not too big of a concern if you have to move it to another computer it's really just the software that tends to matter more so what do you do if something goes wrong suppose that you screw up and you accidentally delete a file and just because it's late at night or you're being careless you actually delete the file or perhaps you do something even more realistic which is you have a really important file on your desktop you open up Microsoft Word or Excel to create a new document but you accidentally overwrite the original one which is even easier to do than accidentally deleting the file well what can you do if you need to get that file back well it sort of depends the advice I think depends on the severity of the situation on the one hand you can get on google for instance and just google something like recover excel files or recover jpeg files personally there's no one program in this world in this realm that I recommend specifically for that you'll get a whole bunch of options if you go to download.com and search for something similar you'll find a lot of shareware programs things that you have to pay probably a few dollars for maybe in the $0 to $50 range if something worse happens where you lose something that's business critical like that powerpoint presentation that you really need or the financials that you really need or your whole life's work or the essays you've written or your stories and what not if it's really important frankly the right approach is probably to outsource it to some data recovery company there's a catch though with this what's the downside of mailing say your hard driver you know overnighting it to someone to do it for you do you think what are the concerns that might come to mind being a consumer here okay so there is that right you're literally handing your data over to someone else and whom you don't have any kind of attorney client privilege with some random people you found on the internet many of you have probably read stories where some idiot goes into Best Buy with his computer for technical support and God knows what the tech guy finds on that computer and they usually end up calling the local authorities you're putting your trust in some third party that will either maliciously or because they need to it's their job start poking around or what else might be a concern when outsourcing the recovery yeah you could make the problem worse right if you're having a clicking sound coming from your hard drive that you can hear just by putting your ear to the computer or to the laptop well that usually indicates a hardware failure and if you're jostling this thing around by dropping it on a FedEx truck and what not that might just exacerbate the situation unless you're pretty careful and the biggest one and frankly the one that would probably shock most of you would guess how much someone might charge to recover a 200 gigabyte hard drive that suffered some kind of problem will be vague actually that's not bad so I mean you'll look at prices upwards of $500 $1500 depending on how quickly you want the data how much data you want back and how severe the problem is I mean as Dan was hinting at there's a bunch of things you can do when it comes to recovering data because if you accidentally deleted a file well there's a lot of tools out there that smart people can use or write themselves to go find the JPEGs you accidentally deleted or the Microsoft Word document that you screwed up if it's a hardware failure though that's when the costs really go up because you need expertise you need people and you know gloves and a white suit in a clean room something where there's not much dust because even remember our video if you get a speck of dust underneath the read head even worse things can happen you need to pay for those kinds of facilities and if they need to start replacing hardware as Dan was saying replacing like the logic board on a hard drive they have to go find the matching part to attach it to your hard drive just to then connect it to a PC and pull your data off so just realize that for the most important data out there you will probably end up paying for it at least if you go with someone particularly reputable and the one that I was going to recommend before turning back to Dan here is a company called Drivesavers which is on my computer screen not on the overhead for some reason they're sort of the de facto standard in the space Drivesavers.com but the catch is that they charge you for it I have to agree I worked in IT at MIT's IS&T department for a while and we referred a few of our clients to Drivesavers and they pulled off what our clients considered miracles literally hard drives that had been underwater and had been run over by a car were able to be at least much of the data was able to be recovered by them it is actually pretty impressive but there is a way that we can just sorry excuse me there is a way you lose projector privileges for that okay so if I can just take a quick step back when I was fumbling about earlier when I was trying to remember the specific software for Windows users I took a minute to find it and it is this TrueCrypt it is actually free software that you can download and I believe it has a variety of options I haven't actually used it myself but I know people that use it and they swear by it I believe there are options for you to encrypt an entire hard drive and there's even ways where you can encrypt a hidden disk image or a hidden image inside of your hard drive so that you can have this sort of plausible deniability and say well oh I don't have this data on my hard drive and there's no trace of it even though it is encrypted even though you know very well that that data exists and there is certainly good and bad reasons for having such power and such encryption at your fingertips but do take a look at it it is very interesting software and it will maybe allow you to get out of some sticky situations so how can we if we can go back to this idea of having a hard drive failure and needing to recover all of this data how can we just mitigate this problem to begin with how can we just not have this become a problem in the first place clearly hard drive failures happen but what can we do to protect ourselves yes yeah back up clearly back up back up back up everything and I really cannot stress this enough when I was in this same job we had so many people and literally all the stereotypical stories of doctoral candidates who have lost their four-year-old thesis because their hard drive suddenly died and oh this can never happen to me it doesn't matter what kind of computer you have Apple computers PCs really doesn't matter hard drives are going to die I've had way more hard drives die on me than I can ever count and if you were paying attention to that to the disk let's see to the disk utility that I had up on the screen just a little while ago you may have realized that I have an absolute ton of hard drives and that is because number of them are used just for backup I have a couple of hard drives that are used backup inside the machine I have one hard drive that's external to the machine and the reason for this is I've actually had one of my hard drives die and then one of my backups die because I hadn't tested the backup in a long time so I lost a lot of data even though I was backing up so just at least just have some backup which is a different hard drive than the one inside of your laptop or the one inside of your desktop external hard drives are relatively cheap these days and even if they are too expensive you can even get a very large capacity thumb drives where you can save your even most important information if you can't back everything up just back up the most important stuff and I really cannot stress this enough because you will save yourself a lot of headache and a lot of money if you have to send your hard drive to say drive savers in order to recover this really important project or really important data that you absolutely must have do you mind clicking me back over not a fan of product placement but I do like to talk about toys I have and it's perfectly on point in this case as Dan is saying what Dan is alluding to actually with his own computers is this technology called RAID a redundant array of independent disks this is a technology that's been around for many years but only in recent years has it begun to seep its way into the consumer market long story short what RAID technology allows you to do is comes in different flavors but one of the simplest ones is whereby this is a technology that allows you to put even in your own home PCs or Macs two hard drives both of say the same size and the computer treats them as though it's just one and what the computer will do is anytime it writes data to the disk it will actually write it to both disks simultaneously and the upside of this is that if one of those drives physically fails or starts clicking or just dies completely your data will still be 100% in theory on the other drive and now you're sort of in a dangerous state because if you lose that second hard drive as Dan was saying you're really out of luck but if you have a day or so to go to the store go online order another hard drive of the same side what RAID also does for you is rebuild itself so you can take out the bad hard drive throw it away or destroy it if you care about what's on it put in the new hard drive and even though you might have to follow a few menu prompts to make this happen you can rebuild the array the cluster of two disks that you have so that it copies everything from old drive to new drive and now you're back at double capacity and one of the neatest toys frankly I've gotten in recent years is this product it's called a Drobo and it is if you remove this faceplate here it's essentially the height of four 3.5 inch hard drives so you can fit one, two, three, four hard drives on top of one another these are SATA hard drives so they're just like the hard drives in most of your PCs and Macs today and you go on Amazon you go to Best Buy you go really wherever buy the right size hard drive and then you remove the faceplate of this thing and you just slot them in and what the Drobo does for you even though it's proprietary is implement the same idea of RAID whereby in any of the four drives one of them can fail and your data is actually very cleverly still stored on the other three so you can rush out to the store by a new fourth hard drive plug it in it then does then requisite copying so you're back at 100% safety and you can again lose another hard drive after that and what's beautiful frankly about this particular product is it makes what has for years been a very sort of esoteric feature of computing RAID and really brought it down to the lay person level where you plug the hard drives in you attach it to your computer via a USB cable and you've got a really big external hard drive and what's also compelling about it is not just this redundancy feature it appears to you as though it's just one hard drive externally connected even though there's four there so if six months from now twelve months from now the prices continue to drop and you can get a two terabyte drive for the price of a one terabyte drive a year ago well that's fine you pull out the one terabyte drive you give it you know a hand me down to someone else plug in the new one and now you increase your capacity incrementally it's really a neat product frankly it's not cheap it's like five hundred dollars still but the flexibility and perhaps the peace of mind you get with your data is a nice thing so worth perhaps considering who's the good cop here anyway okay and now that's now we're back from commercial break I really I wanted to talk about the job a little bit more yeah I wasn't going to praise it I was actually going to say it is actually really really expensive I think you for the cost of one Drobo you could literally get four or five one terabyte drives and that's a lot of money it's it's a lot of space and so if you have if you are very concerned about it and you just want the ease of use and the convenience the Drobo is great but if you want just to put a little bit of elbow grease into it and save quite a bit of money you can actually build your own external hard drive it's very very easy all you need is a hard drive so an internal drive I mean I guess that it's pretty obvious but you obviously need the hard drive but then you can also buy what's called an enclosure and the enclosure the trickiest part is just buying the right enclosure you need to make sure that the enclosure can has has a connection inside of it that matches that of the hard drive that you're buying and there's only a few there's there's seda and there's also ID you're at a you pick one of the two you just buy the matching enclosure matching hard drive and you just literally you you can slide in or you might have to use four or five screws and you screw in the hard drive and then you have an external drive and this is almost always cheaper but it is almost always exactly the same thing as these pre-built options that you can get from Best Buy or Circuit City or whatever online store you generally will save maybe about 30 or 40 dollars in the process for the same size internal hard drive but you're not getting the redundancy you're not but with all this money that you're saving you could buy two or three of these hard drives and enclosures and you could actually just put all of your data on two separate drives it's essentially you're getting the same protection maybe not as easy to use as this but you are getting the same protection so the point of this is that there is not a better way to do it over another the Drobo is great it obviously has it's downfalls the price and my way is awesome but it obviously has it's pitfalls as well but the point is that you do have options to save and protect your data so there's no excuses you really should go and back up your hard drive yes yes so .Mac is an Apple product for its Macintosh computers it's a subscription based model where you are actually given some sets or you're given a certain amount of space in online storage and you can use a backup program that will back up certain files to it online storage is great and personally I think it would be wonderful to you to use but there are some downsides obviously you are sending your data to some other company and even though it's Apple you may or may not trust a company or even the data itself as it's being sent along the wire to be completely private the other thing is that it's just horrendously slow for the same amount of space on a Drobo or even an internal drive or an external hard drive it will just be so much quicker than sending the same data to an online service yes xDrive.com you know this is a very good point so XDrive I don't know much about it but it looks like a more generic form of this .max service where you can upload files to it and it is I suppose one of the positives about putting your data up on the internet is that you can access it from almost any internet enabled computer or internet connected computer I would argue that that's more useful in terms of shuffling data or transferring data rather than backing it up because a backup solution most of the time you just want to have it backed up and it's not going to be necessarily some very small subset of data you want to back up as much of your data as you can and so while you certainly can use online options such as this to back up your data I'm sorry? I'm good okay we're going to so yes so XDrive will actually close but there are other services out there that do essentially the same thing as we've been talking about one of them of course is .max but I would argue that these aren't so great for backing up because it takes so long to send all this data but instead very good to back up maybe very very important or very small files that you want to back up onto the internet and some cloud or some cluster of computers or more specifically maybe you just want to shuffle files from one computer to another without having to use a CD CDR or a thumb drive or something like that can I comment on these other three that they're talking about? Box, Net, Carbonite, Elephant Drive I have no experience with any of these so unfortunately I can't say I do have experience with .max and it was now it's not called .max anymore it's now mobile me and when they changed to mobile me last year September or no not last year it was just this summer just a few months ago they had a lot of problems in the transition but now things seem to be up and running and smooth can you go to me.com and it is actually very good but it is very Mac oriented that doesn't mean that you can't connect to it using a PC obviously David has gone to this website using a PC and you can access all of your files and it has a number of other services as well but Apple really markets this towards the Apple user base or the Macintosh user base and just very quickly before we go into a break I just want to talk a little bit more just make a more specific mention to RAID that David had mentioned earlier so he mentioned what's called RAID mirroring which is essentially you have two or some set of pair of hard drives you can have four hard drives and one hard drive mirrors the other in terms of its data so they are almost exactly the same however there is another kind of RAID option that exists and if you're interested in RAID you really should know the difference between the two before you start playing around with it and it's called striping it basically takes all of the advantages of mirroring and throws it out the window and it has other sets of advantages so let's just take a step back really quick and in mirroring what do you think the downside might be of having two hard drives that have the same set of data on each yes so it's wasted space right so you have to have two one terabyte drives if you want to have a terabyte of space for example but there is something else yes makes you twice as vulnerable to have your stuff stolen so I suppose that depends on whether or not having two hard drives makes you any more likely to have just one stolen than just one hard drive but I think that certainly is a possibility if someone were going to come into your home and just take one of your hard drives the probability of it being that one hard drive is then greater because you have multiple but I'm not sure it's a security issue so let's just talk a little bit about I mean it's the same question is out there but now remember that what we are doing is writing the same set of data twice so what might this mean uses more energy but more specifically it's slower because it takes it doesn't necessarily take twice as long because both hard drives can write at the same time but it's not going to be the fastest thing that's around and that's where this raid striping comes in so now rather than having sort of automatically backed up hard drive you now have to have two hard drives what it does is the computer will send as it's writing data it will send some of the data to one hard drive and the other data to the other hard drive and it will just be able to write it very very quickly on to both hard drives so it's not that you now have a mirror of the hard drives it's not a backup per se what you have is you have some set of data on one hard drive and another set of data on the other hard drive with the advantage really just being speed it's a lot faster to write to two hard drives you know alternately rather than to the same data writing the same data to two hard drives at once so it's very important that you be sure to mirror your drives if you want the backup or to use striping if you want to use the performance so there really is again this give and take when we're talking about all these things and for what it's worth I actually think we're living in a very interesting and very primitive time I mean the fact that each of us in this room has to worry about the failure of our hard drives and the fact that each of us has to worry about backing up is just really not a very efficient approach to things and I think though there are these security and privacy concerns about where you're putting your data and such I mean personally I think this is inevitable I wouldn't be surprised if it's just a few years when most of us are using things like Gmail for our email such that it's no longer sitting on our personal computers at all our data is being stored similarly on servers cryptography though and encryption does offer some reassurances that even if we're putting our data on Amazon servers on Microsoft servers on Google servers at least they can't read it in theory if only we know the password but again there's that tension where if you forget the password and Google doesn't know it well no one's going to get your data for you so there's these competing concerns but I do think there's some exciting times ahead maybe five ten years from now where a lot of this complexity and a lot of this need for a course like this to sort of explain this option and this option and what you do to fix this will hopefully begin to go away as things are simplified and centralized you'll get much better economies of scale certainly unfortunately that's not the case right now so here we are having to explain all these things okay let's just take a quick five minute break and we're back so we've talked about passwords before and odds are at least one of you in this room has at least one password that's laughably easy to guess or to figure out so this might be a four digit ATM code which does not have that many digits and therefore there's not that many options maybe you've used a name maybe you've used a birthday maybe you've used anything that we might be able to gather just by knowing a little something about you so how does how do technologies say like ATM machines mitigate this risk whereby if someone only has a pin code that's only four numbers long that's not that hard to guess right if you have a bit of free time you can try punching in a whole bunch of them so what do you think an ATM machine does in the event that someone is trying to hack into someone's someone's account yeah yeah exactly so you can sort of audit the process and you can simply have the ATM machine suck the card in and just not give it back if you've tried logging in say four times too many or ten times unsuccessfully so computer systems are the same way many computers if you try logging into a server or even some personal computers and you give the wrong password say ten times in a row hopefully they're not going to lock you out in perpetuity since then everyone sort of loses but what do you think they probably do to at least sort of mitigate this threat there what would you hope your own laptop would do yeah yeah so most computers if they support this feature at all they'll lock you out temporarily because if they make you wait five minutes ten minutes odds are it's not going to be a deal breaker overall it's going to annoy you perhaps but at least it's going to make that bad guy sort of continue on his way or at least slow down the process of hacking into your computer by so many minutes that it's just not worth trying to get into your computer anymore yeah so give you a secondary question so a lot of banking sites now actually have this feature where they show you a picture that you've had chosen in advance and then you have to identify that picture that alone is more of a marketing thing than a security thing because even those things can be circumvented so realize two and we won't go into too much technical detail with that particular example but realize that there's also this tension in the world between or this reality in the world whereby some of these security features are touted much like various national security measures really just to assure you that this site is more secure than it actually is and by creating the illusion of some fancy new feature can banks kind of assure you yes yes choose us come to our bank because we have the site key feature and we have this other feature but if you really poke around in these number of these features including Bank of America's including ING directs even those things can be hacked not very easily it doesn't mean your money is particularly at risk but it does mean that it's not as much more secure as they'd like you to think it is in fact we thought we would open up this second half of tonight with a video clip from a movie that hopefully some of you recognize and even if you don't it's got Mel Brooks in it and perhaps speaks to just how laughably easy some people perhaps some of us included passwords are to guess so a little excerpt here no it's not what you think it's much much worse if you do not give me the combination to the air shield Dr. Slutkin will give your daughter back her old nose I'll miss your new nose but I will not tell him the combination no matter what very well Dr. Slutkin do your worst my pleasure the combination is one one one two two three three three four four four five five so the combination is one two three four five what is the combination I've ever heard in my life I turned off the wall I played and you turned off the whole movie bitch gives great helmet PG-13 where's the key it works sir we have the combination great now we can take every last breath of fresh air from planet to India what's the combination one two three four five one two three four five yes that's amazing I've got the same combination on my luggage prepare space for one for immediate departure yes sir and change the combination on my luggage space balls the movie so we promised earlier a look at some of the data flowing across the air in this room what I downloaded was a program called wire shark the disclaimer I need to give is that do not try this here on campus but appreciate though just how relatively easy this was to do right before lecture began I went on google I googled wire shark because I knew the name of the program I click download it's a free download I installed it didn't even have to reboot and now I brought up the software here it's a little non-obvious at first what you need to do but generally you can follow just one or two options actually let me instead go up to the capture menu I'm going to go to start it's going to ask me what I want to start with so I'm going to choose an interface looks like the only interface of mine that has an actual IP address and is in use is that one in the middle the Microsoft device I'm going to go ahead and click start on that one and what you'll see is what we saw before with all the packets in this room that are flowing past appearing on my screen and there's not all that much traffic here at the moment and in fact I think this is actually using a filter right now so that we're not even seeing all of it but again the worry here is that if you're doing something that is like instant messaging or email or pulling up facebook profiles it is not that hard for someone like me to just go and click in one of those packets and look inside of it we talked about tcpip a few weeks ago we talked about the data that's actually inside of those packets besides just the IP address and such but the actual content of your message and your emails well literally programs like this make it as relatively simple as double clicking on a row in this table as it's flowing past and taking a look at what that most recent instant message was so in the spirit of good cop bad cop me being the bad cop how do you actually defend yourself against something that my god is so easy to do once you know where to look for it and again I placed the burden of the answer on you guys how could we protect ourselves from this yes have encrypted wireless okay so that's very good idea for a home network let's say you have your own router and you want to protect yourself using what's the one that we said that you should use WPA because web or WP the other option is unfortunately not very secure but let's take a look at something over here once thought safe WPA encryption is cracked and in fact now no longer is WPA much much more secure than WEP it's only marginally so and so we have again a problem that we still cannot really we still cannot fix using something like this even if we bring our laptop here on harvard's campus where we just don't have the control over the network to be able to encrypt the wireless network many public networks such as harvard well it's not that public but it's relatively public given the size of the number of people that are using it but things such as starbucks wifi or mcdonald's or whoever else has these public wifi locations generally are not encrypted so how can we protect ourselves against attacks or people like david using wireshark in a public location like that if we can't set encryption at the source can we do anything I see some half raised hands any ideas yes so yes there is there are some ways that we could force an encryption so every time you use a secure website so rather than using HTTP for example if you have the option to use HTTPS now all of a sudden that website one specific website only is encrypted and most banks have this encryption now not now I mean they've had it for a while but many banks have this encryption where you can now communicate with the website relatively securely even though you may not be on a very secure network but this only will help us in terms of websites or specific web pages that we can visit in order to or web pages that we can visit that enable this secure HTTP or HTTPS there is another way though if you have access to some corporates account or even here on Harvard what you have access to are big pools of computers that allow you to VPN in so we talked at the very beginning of this lecture about VPN about how you would have an FAS account and you would use it to VPN into Harvard's network essentially what this does is it makes your computer think that it is on Harvard's network the Harvard network will give your computer will assign your computer basically a Harvard IP address and so you can then access web pages as though you are on Harvard's website but the other upside the advantage about using VPN is that just about every VPN tunnel that you create is encrypted so now whenever you visit even unencrypted websites if you are VPN in you have websites that are encrypted from your laptop over the air wirelessly all the way to Harvard servers now as soon as the other end of that tunnel so VPN they call them tunnels and you can think of it like that where you are creating this sort of direct connection secure direct connection between your computer and Harvard's main center or the collection of computers that they have there now all of a sudden your unencrypted data is encrypted between you and Harvard however once it reaches Harvard it is unencrypted and sent unencrypted the rest of the way but we have now eliminated this possibility of David peeping into what we are doing online because all of the traffic is now encrypted oh sorry interrupt terribly slightly but who does still see what you are doing on the internet the network administrators at your company right whoever is closer to your data at that point so there are rarely perfectly good solutions to this because even then is your data once it leaves the company going out on the broad internet now granted there is so much data on the internet's backbone that most likely you don't have an enemy who is sitting in the middle of the country looking in the hopes that your data is about to pass through some particular router so you sort of have security through obscurity and that your data is going every which way and clouded by a whole lot of other data so really some of these suggestions are really just about pushing your expanding your privacy boundary so that they are at least beyond your immediate threats and that might be the person in starbucks next to you it might be the students in the room next to you here but one of the most important takeaways perhaps is that unless you are using an encrypted program or an encrypted protocol that's pretty much out of luck if you're pulling up web pages cnn google and what not anyone in this room can see what's going on by nature of how the web is structured and by nature of how those websites are structured because they don't use what protocol that we talked about weeks ago yeah, HTTPS if the URL does not begin with HTTPS as opposed to just HTTP it means it's unencrypted which means anyone between points A and B and in a wireless room that's everyone can view the data going across the wire so it really depends and at least the mentality you should now go into starbucks with and the like is it depends on what your threat model is like who are you worried about and what kinds of acts are you doing that you might care about fortunately a lot of email servers are encrypted these days so when you send an email from Microsoft Outlook it's possible but not a guarantee that your SMTP server will actually encrypt the email as it goes out but again as soon as it leaves your ISP servers or your company servers out it goes on the public internet unencrypted unless you're a bit fancy and have special encryption software installed fortunately most websites even if they don't encrypt everything they do encrypt the really important stuff like user names and passwords so MySpace and Facebook things that do you really care if someone sees your profile even though you don't you rather they not but you probably don't want anyone to see your username and password or at least your password so very often for again performance reasons cost reasons in some sense do websites only encrypt the really important stuff like user names and passwords and then once you've typed in your password they send you back to the HTTP version of the site one huge exception to this though is what types of sites always maintain HTTPS sites like usually banks where they sort of have more to lose they need to reassure the public more maybe they have more money to throw at the problem so they can have beefier servers to handle the encryption back and forth those two if you're really just worried about you know covering make my screen appear if you're really just worried about covering your tracks or at least sort of pushing the knowledge of what you're doing online out a bit further you can use what are called proxy servers or in this case this is a specific example that's been around for a while anonymizer.com and this isn't to say that this is going to truly anonymize your traffic but the idea of it it's always kind of fun to see people like this what's useful about a site like this is that essentially you tell anonymizer.com what URL you want to visit it then goes and fetches that web page and then it returns the web page to you the implication being whose IP address shows up in that you know sketchy or non sketchy websites logs theirs not yours right but again you're just kind of truck putting your trust in someone else no longer you trusting say the website itself but now you're trusting whom like these guys right and you're paying them money but they don't have any personal vested interest other than you know maybe their reputation for protecting your data odds are well maybe they're very careful about maintaining logs but certainly in this country has there been a movement federally for companies for ISPs to maintain much more data on you and it's quite possible that a company could be subpoenaed for their records as to who was logging into their websites so realize too you might be paying for the service yeah but that doesn't mean you're necessarily getting what you're paying for and I'm sure if you read the fine print they probably do have to make clear that you're not necessarily truly anonymized but there are other fancier technological solutions here so this is a free option called tour and this was this sort of developed as a research project what tour is in a nutshell is in anonymizing protocol whereby you download their software freely available when you then boot up your computer and run their software your computer sort of uses some fancy algorithms to find another computer relatively nearby that's also running the same software so it's peer to peer in that sense if you remember programs or if you use programs that are that are peer to peer in nature file sharing in particular what your computer then does is it finds a computer and then it sets up similar in spirit to what Dan called before the tunnel so that you can send traffic from your computer A to that other computer B meanwhile you've probably set up some tunnels to some other places too and those guys in turn have set up some tunnels as well and so what tour tries to guarantee is that when you request a web page send an email send an instant message that email or instant message or what not doesn't travel directly to the recipient or directly to the website but rather it goes through this stranger then through this stranger then through a third stranger whose computer then forwards it out on the rest of the internet and so the implication of that now it's sort of like in the movies when someone was trying to prevent their call from being traced and you have this silly little global map and it's like sir we're tracing the call and they're showing you the line bouncing from here to here to here to here because the person somehow was routing their call or whatever it was from spot to spot well that's really what tour does and you pay a performance penalty unfortunately it isn't the fastest thing in the world and even here too you've got to trust that stranger down the road or in the next city over because they could be looking inside of your data if encryption's not actually being used so again there it's a trade-off and I think what's empowering about at least hearing about these things is that you at least know the options and you don't get the the will pull over your eyes by someone just saying oh use this because this will protect you and you have to push a bit harder on claims like that that's true but I do think that some of the other attacks if they were to happen to you would be at this sort of more public level so this idea of someone else in the room for example using Wireshark or some equivalent to be able to look at the packets that you are sending back and forth which could contain very private information very personal information in order to protect yourself from that you could use something as simple as a VPN to connect to Harvard so even though myself and David went into detail about even though that data is no longer encrypted from Harvard's end arguably that's not such a big deal because what you want to protect yourself are from the major points of attack which could be this public place for example so even though we here in this classroom aren't likely to be spying on each other you have no idea what someone in a cafe or a Starbucks like place could be doing to try to attack or to gain your personal information how easy is it for someone sitting in a Starbucks next to you to gain access to your computer and look at what you are doing or even start controlling it so that really depends I think pretty much for all of you it's not really a true concern where it might become a concern is if you enable some features such as Windows remote desktop or Apple screen sharing where all of a sudden you are intentionally allowing people the ability to access your computer even with all of these though it's required to have a username and password but if you have a very basic username very basic password it would not be difficult for someone to gain access and then they could literally see your screen and it's very similar in spirit to what I was doing before where I was showing you the hard drives that I had in another computer and I was literally just using the Windows or the Apple screen sharing where now I am just logged into my computer that is sitting at home and so it's generally not it's probably not a good idea to have this enabled on a laptop especially if you have a very basic or very easy password very password that is very easy to guess but it's generally okay if it's at home it's behind a closed network and you know that you will generally be the only one trying to connect to it but accidents happen I mean I believe it's true that in the computer science building on campus and they might not have even fixed this yet one of the printers is a network printer which means everyone in the building can print to it but the internet is over in IT there not so good with the security such that anyone on the internet could print to this printer and I think we were getting some guy from China's emails once in a while because he thought it would be amusing to print things to our printer in Cambridge, Massachusetts just because it was there so I mean if you poke around and you have the right tools you can look around on local networks and see not just wireless traffic like this but very specific folders that people might have shared very often by accident because it's relatively easy to do and it's not like it's not obvious to the user or the owner of the computer that they're back doors wide open so to speak That's true there are other protocols besides this literal interpretation of your question of literally seeing everything as it is per pixel on the screen but you could also just gain access to the files so not only this but it is possible to have some file sharing enabled and Windows file sharing for a number of years was particularly prone to being hacked and I think even on some installs being enabled by default that it was just very easy to guess someone's password because most all Windows installations have the username of administrator so all you know all you need is administrator and someone's ridiculously easy 1, 2, 3, 4, 5 password then you have access to the files on their computer so that is yet another point of attack but as long as your computer is as long as you don't have these things enabled on your computer and I can show you on a mac it's under the sharing pane and the system preferences you can see I have nothing enabled here you're pretty much safe from these sorts of attacks of course you're not completely safe there are new attacks that come out daily where someone could somehow gain access or execute code on your computer but for the most part you're not doing something stupid and just welcoming people to your computer so we tonight's theme is clearly threats what concerns keep you up at night or what have you been told or heard that is a threat to you that is worth dissecting yeah not necessarily hack into so recall when we discussed wireless a couple weeks ago a wireless router a wireless access point has that SSID the name that identifies it and you can have encryption on like WPA or web or off so often times in an apartment building and even in a local neighborhood people will have home routers that are wireless that don't use encryption so yes anyone close enough where they get a good signal can just connect to your home network but that doesn't necessarily mean your own data is vulnerable even though now that user is connected to your homes modem or your homes router the implication of which is they're now using your Comcast connection or your Verizon connection only if your computers at home have say file sharing turned on in an insecure way or your accidentally or intentionally sharing files can those people actually get into your data so this I mean this is the case even in my apartment where I have a wireless access point but I do use encryption but the fact of the matter is I have friends who come over who just want to get on the internet and I'd be a little ridiculous if I didn't let my friends use the internet just because I was worried about letting them onto my network so I sort of mitigate that concern by just making sure that the files that I do intentionally share in my home are password protected and themselves encrypted by a various means so that yeah my buddy can get onto the network but only if he sits there and really tries to hack into my machines can he maybe make forward progress but it's not just there by nature excellent question other questions yeah oh that's the name of the access point it's it's a good question so just to summarize if you are connecting to someone else's access point whether it's a neighbors whether it's Comcast or rather whether it's Starbucks whether it's Harvard's yes anyone in the vicinity or anyone who physically owns the device to which you're connecting to in which in this case the neighbor absolutely they could be looking at everything going back and forth as for the security of your own computer it again boils down to what Dan was talking about if your computer is accidentally sharing files or you have no passwords whatsoever then absolutely you've just connected yourself in such a way that now they have a direct path into your computer so you need to be careful about that odds are they didn't even notice many home routers don't make it very obvious that other people are connected unless you know what menu option to click but there's a good point article in slash dot or some other publication online geeky magazine type thing year or two ago now where some guy who had way too much free time on his hands and was running a router that I think was running Linux an operating system of some flavor thus giving him more control over how it works he just thought it would be a blast to leave his access point publicly accessible so no encryption so that anyone in the neighborhood or vicinity could connect to it but he wrote some software access point that would anytime the user requested some bits from the internet that included a JPEG like a photograph it would flip the image so that the users if they visited web pages all of the images would be upside down and that is a nightmare of a problem to try to debug because you have no idea what's going on and what are the odds that some guy with way too much free time is going to be flipping your JPEGs upside down just to mess with your mind but these are the kinds of things you can do which is on point you don't have total access to whatever is going through the router so it does show the power that someone who owns the router has over you because you are basically trusting that this router is transmitting your information to and from a server accurately but to go into a little bit more detail not only did he do that this image flipping he only did it for people that did not have proper access to his router so he figured out some scheme of telling the router that he was his laptop and all of his images would come in okay but everybody else he assumed was false and I think every day he would do something different with the image so one day it was flip it the other day it was make it really fuzzy and all of these other things make it like purple tinted or something like that but it does go to show that if you do trust these devices you are you are placing this sort of implicit or explicit trust in them that they are not damaging or recording your data in any way but this is only data that you are sending and receiving actually connecting to your computer to obtain some information via files using some file sharing protocol for example that would require quite a bit more malicious intent and some intentional hacking for lack of a better word into your computer to try to gain access to it unless you are literally transferring all of your so I guess we could go full circle with this and if you are sending the entire contents of your hard drive to be backed up over some insecure means, insecure means someone between yourself and this remote server could be accessing your unencrypted data but that is an entirely different attack than what you were referencing before there is a fun opportunity here to tie material together so let's hypothesize for a moment this guy that was messing with people's minds and thus making sure his images came out fine but everyone else's images coming through his router were flipped upside down like can you put your finger on in an engineering sense how he could have distinguished his computer, his traffic from other people's so he could find his IP address which belongs just to him presumably and then just say anyone with a different IP address should not have this happen to them let's suppose let's push a little harder as you know IP addresses can change because of DHCP might change every time he boots up his computer so it might be different every day okay so you could set it to a static IP address so say always give me this but let's push a little harder what else could he do so that so-called MAC address so remember that duality of addressing in computers you have the IP address that's sort of up here and then the MAC address the Ethernet address that's conceptually a little lower a little closer to the hardware one is like the unique serial number that doesn't change one is the IP address the logical address that does change so either of those might have been viable options and who knows maybe he did it in a different way altogether the neat thing hopefully is that you too can hypothesize now how he might have done that I can play bad cop for a second actually it is certainly possible to use the MAC address and it's as if you remember the MAC addresses are very long and very difficult to guess however it is possible for a computer to spoof a MAC address so even though this even though all of our laptops that are connected to the wireless network are communicating their MAC address with some of Harvard servers for example for DHCP is just one of the examples it is possible for somebody else to come on and spoof their computer as mine by just by taking my MAC address but they have to know it obviously but it is possible to be able to spoof that as well and not even I mean I'll push a little harder there so you are some miscreant with a laptop in the Harvard yard you want to get on the internet you have some savvy and you don't have a Harvard ID therefore you can't register your computer and to turn your Ethernet address your MAC address but you are determined to get on this network well we've just seen that it's not all that hard with someone with an internet connection and you know a bit of SAP oh make my screen appear I don't have a button so it's not that hard for someone to sniff traffic and if I actually look closely inside these packets besides the actual information going across the wire what else is in there the origin the destination otherwise where is that data going if there's not some remembrance of where it came from and where it's destined for so you can even figure out in theory someone's MAC address just by sitting next to someone suspecting freshman in the yard and then as soon as they amble away and leave their internet connection you just steal their MAC address and get on Harvard's network so granted Cambridge has free wireless now as I recall so maybe not such a big deal anymore but certainly the possibility remains if you have sort of the time and you know the incentives to do such things other threats that come to mind or have worried you or you've been scared by because someone else said it was true Trojans what's a Trojan this is like the confessional of the classroom over here tonight okay so a Trojan is an example of and you can spin this different ways an example of what most people would call some kind of virus a virus being a malicious piece of software that believe it or not someone has taken the time to write these viruses do not appear in the wild because of mutation or any physiological origins but because someone would again too much free time sat down and wrote it for fun because they could wrote it for financial gain just to wreak havoc but all of these viruses all of these worms which are similar in spirits of viruses that have appeared on people's computers over the years are written by people and sometimes you know 12 year olds in other countries 18 year olds I mean it's usually some fairly introverted person it seems who lives in their basement or their bedroom mostly and then makes the idiotic mistake of bragging to strangers in a chat room which is seems all too often how these people are caught but there's a lot of dangers out there I mean if you buy Norton antivirus McAfee antivirus any of these commercial products these days they recognize thousands of different threats that have been released on people's computers over the years some are very similar to others because it's a lot easier to take an existing virus tweak it a little and call it your own but there's a great number of threats and as your story sort of hints at this being a Trojan the idea being from the Trojan horse era where you have a piece of software instead of a wooden horse on someone's computer and it outpours bad things that can do anything and this is the problem a virus is just a piece of software that someone written so if you can imagine a good guy or a bad guy writing a piece of software that software can take the form of a virus which can be sent intentionally or unintentionally via email to other people a worm is pretty much the same as a virus but a worm doesn't need a person to accidentally click a link or to forward it to someone else a worm is self-propagating which means once your computer is infected with a worm it will spread to other computers if it can without you ever opening an email without you're doing anything so viruses like the word implies require a host like a file so files get infected because a virus attaches itself to the first few bytes of the file in the middle of the file at the end of the file and so when you open that file and trigger those bytes to be loaded into memory or executed bad stuff actually happens worse because it self-propagates without humans needing to intervene what I would argue is that a lot of these attacks so there we do have a lot of worms viruses Trojans that exist that are problematic for our computers but what seems to be the biggest problem aren't these programs it's literally user error or users trust in some event that is occurring on a computer that hackers can exploit and there's a lot of social engineering that goes into this and phishing is just one example and we'll probably talk more about that next week I'm guessing that really uses the sort of social engineering or this aspect where we are assuming trust in some particular device or some particular event that is taking place and someone is using that against us to their advantage yes still taking notes what I thought is all these new parcels and those stores getting their database in this pack whatever happened then I guess somewhere there's just a copy of my credit card number all the way to the site and that's just that one because I'm just buying one thing you might be more expensive online I'd be a putter going to another credit card I'll see if it's that stuff how much is your worry so that's a good question so repeat for camera credit card transactions online how secure are they so the transactions themselves are pretty secure at least in principle you no longer have a human on the other end of the phone you no longer have a stupid piece of black carbon paper that has an imprint of the numbers which can be stolen or copied elsewhere there's no human involved in almost all of these online transactions so in that sense I would argue that most online credit card transactions are more secure because there's no middleman no human and the bits are just going back and forth quite quickly I would add between computer or you and another computer the server but the catch is as you know those servers are very often saving your data because you want them to or because they choose to and so more common perhaps than individual users computers are being targeted is the databases of companies so to attack on to tie together our threads with this notion of packet sniffing there was a couple one or two stories in the year to where some guys were sitting in the parking lot of like a lows hardware store maybe it was home depot just sniffing the wireless traffic from the local store and because the store did not encrypt their wireless traffic and because the stores computers their servers inside the building were not themselves very secure these guys were literally able to sit in their car and grab data from inside the building because it was not very secure unfortunately they like a lot of these idiots stayed in the parking lot too long eventually got caught the point though is just how accessible this data was frankly when it comes to credit cards I think we're at a point technologically where that's a problem for political protections commercial protections I mean I trust that annex will deal with the fraud issue if my credit card is stolen and I think realistically unless you're going to live in a cave without using online transactions at all you really lose control over a lot of that kind of data but I would say these days for me certainly it's an acceptable risk I think nothing of you know using my credit card because I monitor my statements and annex does the same and they have built-in protections so I think that protections there are not so much technological as they are policy oriented if I can bring this even more full circle we were talking before about how important it is to back up all of your data will companies certainly do this with your information that they are storing but we come back to this idea of human error views or error where people they may back up all of this data but they may back it up in an unencrypted matter and perhaps what's more of a security risk than them actually storing it on their servers are these idiots these IT idiots that carry around backups of all of this data unencrypted in their backpacks or in their briefcases or whatever and they get stolen out of their laptop and we've been hearing a lot about this not so much here but especially in the United Kingdom in England where this has been happening with government records just all of the time in the past few months and so that seems to be more of the threat than actually using your credit card online and just like David I would argue that using or storing your credit card information in a fairly large well reputed site is not so much of a big deal especially since all of the credit card transactions are verified per transaction hopefully by you actually taking a look at your statement so you can immediately recognize when some transaction was made that was fraudulent and you can identify that and just about every credit card company that I know has very good protections against fraud and you're very well protected against them using your money so often times a lot of the burden of this data protection is placed on the companies because if the companies screw up and they're getting a lot of fraudulent purchases against the credit card company will push back and not actually give them that money that they were supposed to be given but there are some lines I would draw on this hand so I have sort of accepted for myself that email it's not all that secure I'll sit down in some other country at an internet cafe check my email even though it means inputting my password I sort of accept that as a possible risk my bank account information though for instance I never check it unless I'm on my own laptop or my own desktop at home I would never pull up my bank account at an internet cafe I wouldn't even do it on a friend's computer just because that's the line I've drawn for myself I have no control over those computers and even though in theory I have control over my own computers we all know that things can get onto your computer that you didn't intend to be there viruses, trojans, worms all the same kind of bad software so even then even when you're using your own computer are you trusting that things are okay and so it's I think it's totally understandable to live in a bit of doubt as to just what you should be doing and where I also think there are some rules of thumb and if you take away nothing from me at least tonight it's that I would not check bank accounts on any computer they're the one that you yourself control or know or comfortable with because for me the ability for someone else to just get my username and password and write him a self a check or send some money elsewhere that's sort of too easy and I'm much more worried about cash leaving my account than say a charge being put on my credit card which is more easily reversed than cash coming back in. I think if anything to define your own line of paranoia how much is too much defense and I mean if you were to take all of these suggestions that we've been talking about file vault or true crypt and overwriting all of your data with 35 passes you would spend all of your time on security and none of your time actually getting anything done or if you were just so paranoid that you weren't going to use any of this technology well that's equally as pointless I would argue so you have to figure out what you think are the highest threats to you and defend against those and for the rest you just have to do your best in terms of protecting yourself against them bring us home really all right well unless there's anything else thank you all for coming we will see you next week where we will continue security