So basically shortcut malware is relatively simple and it allows you to execute for example powershell scripts.
Usually when creating a shortcut there is a max argument length that is too short to do anything interesting with it, however if we create a shortcut programmatically using c# for example we have much less limitations on this max argument length allowing us to slip in small payloads. The code below is an example of how to do this. First you need to create a shortcut that will be copied (logo, payload, ...) and then we make a copy of that shortcut and modify only the arguments, the new shortcut gets saved and copy.png.lnk gets appended. I renamed it to copy.png.lnk so you can see that it looks like a png (except for the shortcut logo) and the .LNK is not visible on the end of the filename. The payload in this code is just a simple messagebox popup, and in practice it is most likely needed to implement a downloader which runs a downloaded powershell script because there is still a limit on how much data you can pack in one shortcut.
If you have any questions feel free to ask
program.cs:
Usually when creating a shortcut there is a max argument length that is too short to do anything interesting with it, however if we create a shortcut programmatically using c# for example we have much less limitations on this max argument length allowing us to slip in small payloads. The code below is an example of how to do this. First you need to create a shortcut that will be copied (logo, payload, ...) and then we make a copy of that shortcut and modify only the arguments, the new shortcut gets saved and copy.png.lnk gets appended. I renamed it to copy.png.lnk so you can see that it looks like a png (except for the shortcut logo) and the .LNK is not visible on the end of the filename. The payload in this code is just a simple messagebox popup, and in practice it is most likely needed to implement a downloader which runs a downloaded powershell script because there is still a limit on how much data you can pack in one shortcut.
If you have any questions feel free to ask
program.cs:
