AutoIT Malware. A detailed analysis


This is a sample that came to my hands by a spam campaign, and caught in a corporate honeypot. Make a comment under this post with your email if you want a sample.

Sorry for some false positive AV alarms while browsing this post.. It was due to some code listings. I removed the AutoIT script, but it can be found here: .

~ Due to big amount of requests, I uploaded the sample here too. Pass is “malware” ~
Here is an overview of what you’re going to see in this post:

1) First malware file: .exe
– recognition of the executable’s type (WinRAR SFX)

2) Drops: update.exe + 3 files
– recognition of the dropped PE (AutoIT), and obfuscated AutoIT script
– making a custom python script of script de-obfuscation
– Clear AutoIT script analysis, methods and some thoughts about it.

3) LoadPE method (by the AutoIT script) using an encrypted drop
– making a custom script to decrypt the drop (RC2 encrypted usign CryptoAPI)
– analysis of the final malware. What data does it collect, which format, how does it send them and where.
– reveal some console log messages of the app by just changing it’s IMAGE_SUBSYSTEM byte from PE Header let’s go..
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