The Trojans we've created so far are amazing; they can bypass antivirus programs – they run two pieces of code, the first one runs in the background, which runs our own code and does what we want it to do, such as opening a port or connecting back to us and giving us a shell, and it runs another piece of code that the user expects. It could display an image, play an MP3, or display a PDF file. This functionality makes it very difficult to detect, so the best thing to do is to check the properties of the file and make sure that it is what it's claiming to be. In the following screenshot, we have a Packt image and we can see that it's a .jpg, so it looks like a picture, it has an icon, and if we run it we will get a picture, like we saw in Chapter 13, Client-Side Attacks - Social Engineering:

Right-click on it and go to Properties...