 Welcome back to this course. The topic of this week will be Advanced Persisting Treth, or APTs. So far, we have assumed that our goal is to protect the target network from attacks coming from the outside world. Here, we take another perspective. Namely, we assume that an attack has succeeded to penetrate the target network perimeter, and it is now active in internal network, for example, by attacking other hosts and stealing information. This week, we will explore the following topics. After this introduction, we will see the basic concepts of APTs and describe how they work. We will then give a talk about that exfiltration and give some practical example. Then, we will look into Stuxnet, which is considered one of the most advanced examples of IPT. Finally, we will conclude.