Understanding trojans
In the previous section, we created an executable that can be run with a single click and you will then have a reverse connection with the victim, but this requires the victim to manually open and click on the executable. Here comes the concept of a trojan. A trojan is a malware program that hides in a very unsuspecting manner. Usually, these trojan malwares are merged or bundled together with legitimate software and run when the victim tries to open a legitimate application or file. You will see that a lot of the time, these viruses are merged with PDF or image files. Hiding malwares inside a trojan is a complicated task, since a lot of the time, the tricks that you learn are quickly patched in the updates for the software that you are using. For example, let's say that you discover a vulnerability in software that allows you to embed malware in a file. Unless you are the first one to discover this vulnerability, it is quite possible that this will be patched...