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Guess what? Yep, there's yet another type of malicious document going around. Like last time, it's a MIME file with an MSO file containing an OLE file.
The sample (schro_193B11.xls 7F8C5E8B7157B04FA8E9CEEF13C28AB9) is an Excel spreadsheet saved as a MIME file:
But this time, the compressed data is at another position inside the MSO file:
So I updated my oledump tool (V0.0.16) to search for compressed data inside MSO files (in stead of looking at a fixed position 50). The string encoding used in the VBA code is interesting. It is reminiscent of RC4:
I also updated my plugin plugin_dridex with this encoding:
Didier Stevens |
DidierStevens 505 Posts ISC Handler May 15th 2015 |
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May 15th 2015 5 years ago |
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So this is just one more attempt to fetch malware per download by a .VBS extracted from an MS office document.
Guess what: SAFER alias software restriction policies blocks both the execution of the .VBS and the downloaded malware! |
Anonymous |
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May 16th 2015 5 years ago |
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Guess what: SRP and AppLocker are trivial to bypass, because Microsoft designed it like this.
"SANDBOX_INERT: If this value is used, the system does not check AppLocker rules or apply Software Restriction Policies." I reported this 4 years ago: blog.didierstevens.com/2011/01/25/circumventing-srp-and-applocker-to-create-a-new-process-by-design/ As a result of my blogposts, Microsoft designed a hotfix to disable this bypass. support.microsoft.com/en-us/kb/… This hotfix is not installed by default. |
DidierStevens 505 Posts ISC Handler |
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May 16th 2015 5 years ago |
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Guess what: I expect every non-idiot using SRP or AppLocker to be aware of this optional update and install it.
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Anonymous |
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May 16th 2015 5 years ago |
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