Skype worms are not exactly new anymore (unfortunately).
Scenario is simply: someone on your friends list got infected and is now sending you a link to a ‘funny image’ or pictures of you. In this case, you are being baited by a video of you. Let’s just hope it’s nothing embarrassing 😉
Lol! Seems like there’s a cool new video of you going around.
When visiting the (totally not malicious looking) link, you get a video, but apparently you need to download a plugin first:
When you click on Install plugin… a new file called ‘setup.exe’ gets downloaded. It’s actually simply a self-extracting archive which contains a file named: ‘setup_BorderlineRunner_142342569355180.exe’
When running the setup.exe file:
It almost seems like we’re installing legitimate software, SkypeFall version 1.0. Almost.
Clicking Next, Next, Next in the setup wizard, nothing much seems to be happening, but in the background there’s quite a lot going on:
A new file called ‘SkypeFall’ is dropped and a new DLL is being registered. Afterwards, two new processes are now active in memory: SkypeFall.exe and rundll32.exe, in which the latter is actually running the DLL BorderlineRunner.dll.
Files are being created in both respectively %programfiles%\BorderlineRunner and %appdata%\SkypeFall. A new service is also registered:
Afterwards you’ll spam all your friends with the same message as well, following the pattern:
We detect this malware as:
How to avoid the malware W32/Skyper.A.worm
- Never click on unknown links, especially when a friend sends you a generic text saying there are pictures or videos of you going around. If you’re really curious, ask them first what’s it about. Better be safe than sorry.
- Don’t be fooled by known icons or “legit” file descriptions, this can easily be altered.
- Even if you clicked the link and you’re not suspicious, you should be when a file is downloaded and no pictures are shown, but just an EXE file.