Static Analysis of Emotet Maldoc
Brad wrote a great analysis of an Emotet maldoc send to us by a reader.
In this diary, I would like to show how this maldoc can be staticaly analyzed with a couple of tools.
oledump.py confirms it is an Office document with VBA macros, as we expected (the M indicators tell us which streams contain macros):
Selecting stream 9 (oledump.py -s 9 -v) shows the code that will execute automatically (Document_Open sub):
As expected, it is obfuscated, but we can still recognize some strings that look like BASE64. If we would manually concatenate them in the right order and decode, we would recover the payload. Fortunately, for this sample, there is an easier way by using an open-source VBA emulator: vipermonkey.
The VBA emulator encounters some errors during the emulation, fortunately for us, while outputing the concatenated base64 payload:
We can pipe this into base64dump to decode the base64 code (since vipermonkey outputs the base64 string as error in stderr, I combine stderr and stdout with 2>&1 to pipe it into base64dump.py):
The decoded base64 payload starts with powershell, so we are on the right track. Let's dump the full decoded payload:
Didier Stevens
Microsoft MVP Consumer Security
blog.DidierStevens.com DidierStevensLabs.com
Comments
Anonymous
Dec 3rd 2022
9 months ago
Anonymous
Dec 3rd 2022
9 months ago
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<a hreaf="https://technolytical.com/">the social network</a> is not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go. The social networks only collect the minimum amount of information required for the service that they provide. Your personal information is kept private, and is never shared with other companies without your permission
Anonymous
Dec 26th 2022
8 months ago
Anonymous
Dec 26th 2022
8 months ago
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Anonymous
Dec 26th 2022
8 months ago
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Anonymous
Dec 26th 2022
8 months ago
Anonymous
Dec 26th 2022
8 months ago
https://defineprogramming.com/
Dec 26th 2022
8 months ago
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https://clickercounter.org/
https://defineprogramming.com/
Dec 26th 2022
8 months ago
rthrth
Jan 2nd 2023
8 months ago