Mysterious case of the executable hijack

I got a message from my friend Paul today asking for help with an infection. He was using the latest version of Firefox at the time and was positive he did not click on any odd links or downloaded anything malicious. Naturally, I advised him to run Malwarebytes Anti-Malware and had him send me the log. One specific entry popped out at me.

Memory Processes Infected:
c:UsersPaulAppDataLocalojx.exe (Trojan.ExeShell.Gen) -> 3508 -> No action taken.

I picked up the phone and called Bruce Harrison, our VP of Research, and asked for an explanation. The result had shocked me. I was told that this was an executable hijack that is used with FakeAlert, a Trojan we see almost daily in our research center.

What exactly does that mean? Well, when the infection is able to penetrate your computer, it hijacks all executables to run the malicious file instead of their intended targets. For example, you try to open Skype and the malicious file starts instead.

It does this in two ways. First, it modifies each shortcut itself to point to the malware. Secondly, it modifies the .exe shell in the registry so that once again instead of starting the correct executable, it starts the malicious file.

Luckily, Malwarebytes Anti-Malware was able to patch Paul up, but we both wanted to know how this had happened. Bruce advised us to check the installed Java version. It was in fact outdated by several versions. I advised Paul to update to the latest version and he now has a healthy computer!