 What's going on everybody? My name is John Hammond. Welcome back to another Pico CTF 2019 video. This challenge is called Pico Browser. It is worth 200 points in the web exploitation category. It says this website can be rendered only by Pico Browser. Go and catch the flag. So we have a link here. We could visit a couple ways to access that URL. And we have the same sort of sign in and sign out that we might have seen in another challenge. But there's nothing particularly there for us. We can hit flag. It says you're not Pico Browser. And it gives us Mozilla 5.0, X11, Ubuntu, Linux, blah, blah, blah. So this looks like a user agent string. So if you haven't heard of the user agent, it's a header that kind of follows along with your HTTP requests. And that means where you're coming from or what kind of browser you're actually using. Are you on Firefox? Are you on Chrome? Are you using Windows or from an iPhone, Android device, et cetera, et cetera. Interesting thing though is that this header can be manipulated and modified by the end user. You can always spoof your user agent. So that's exactly what this challenge is trying to get at, is trying to have you be able to send your own header or your new user agent that's coming from Pico Browser. So we can do that. We can go ahead and simply curl that web page. We have it here. That's forward slash flag. Let's make directory Pico Browser. Hop over there. And now let's curl that location forward slash flag. But it says, hey, you're not Pico Browser. Right now you're coming from curl 7.64.0 or whatever. That's fine. That's not what we really need to do. We need to go ahead and add our new header. We can do that with curl attack capital H. And we need to actually supply the name of the header that we're modifying. It's a user agent and then a colon following it followed by the value that we actually want. So Pico Browser will be our new name, not curl anymore, because that's not the browser we're going to end up using. We are using that to access the page, but we can modify that header. Now we can crank through that and it says flag Pico CTF, Pico secret agent, blah, blah, blah. Let's go ahead and carve that out. I'll use tack s to make curl silent. Let's grep tack oe Pico CTF with the curly braces to denote the flag format. Regular expressions there and color equals none. There we go. That's our flag. Let's go ahead and save that and we can run finish to mark that as complete. And we can copy this. I think I dropped that. We can go ahead and submit that to the web page and get our 200 points. That is correct. So simple challenge, being able to modify it with curl or Python requests or any other automated way to actually access the page is good and quick and easy. You don't have to deal with getting like a Firefox extension or any plugins from the top right to be able to modify it and tweak it. I like it in the kind of command line automated way. So I hope that's cool and useful. That's simply that tack h, capital H argument for curl, and you can modify headers and user agent. You can always manipulate. So thank you guys for watching. Hope you enjoyed this one. Super quick, super simple. We're going to ramp up to some harder Pico CTF stuff soon. See you in the next video.