Dridex Redirecting to Malicious Dropbox Hosted File Via Google

Published: 2015-04-21
Last Updated: 2015-04-23 02:50:25 UTC
by Johannes Ullrich (Version: 1)
4 comment(s)

Thanks to Wayne for sending us in the latest Dridex sample. He observed them arriving this morning around 8am ET. According to Wayne, this malware may use Google Analytics to count how many people opened the file, but I haven't confirmed that. Google redirects are however used to obscure the destination.

Checking my own inbox, I found a couple of the messages in my spam folder. Here is an example I received:

The link is kind of interesting. It leads to Google, but Google will redirect you to the malicious file which is hosted on dropbox. At least the file above was still available.

 

The link:

hxxps://www.google.com/url? q=https://www.dropbox.com/s/ 0c5we7id7mgwk89/ACH transaction0336.doc?dl=1 &sa=D&sntz=1&usg=AFQjCNFvX9uqV7uVjP8NWYKa4xkImgXPBA

Google will show a note that the user was redirected, but the file will download right away. It will not open, and the user will have to open it an enable the Macro to execute.

Hashes of the Word document:

MD5: f12cfa3f42784769c1542155a4f9cde8
SHA1: 5a939df2692091c89b5a75db3bba990aae3b6d10

And a quick review with fellow handler Didier's oledump tool shows indeed a number of suspect macros.

$ ./oledump.py -p ./plugin_dridex.py ../ACH\ transaction0336.doc  -e
  1:       114 '\x01CompObj'
  2:      4096 '\x05DocumentSummaryInformation'
  3:      4096 '\x05SummaryInformation'
  4:     10927 '1Table'
  5:    136110 'Data'
  6:       666 'Macros/PROJECT'
  7:       161 'Macros/PROJECTwm'
  8: m     683 'Macros/VBA/Module1'
               Plugin: Dridex decoder
  9: m     683 'Macros/VBA/Module2'
               Plugin: Dridex decoder
 10: M    3592 'Macros/VBA/Module3'
               Plugin: Dridex decoder
 11: m     683 'Macros/VBA/Module4'
               Plugin: Dridex decoder
 12: M    2526 'Macros/VBA/Module5'
               Plugin: Dridex decoder
 13: M   10321 'Macros/VBA/ThisDocument'
               Plugin: Dridex decoder
 14:      5094 'Macros/VBA/_VBA_PROJECT'
 15:       649 'Macros/VBA/dir'
 16:      7220 'WordDocument'

Virustotal only shows 4 "hits" out of 57 AV tools tested for this binary

https://www.virustotal.com/en/file/efd9e8d6fe04bf8b7abcdd208c7f1b2b2fabf2ae09bce9775631047455cd533b/analysis/1429631351/

 

 

 

---
Johannes B. Ullrich, Ph.D.
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