Data stealing trojan posing as a Text document

December 4, 2015

The Dell SonicWall Threats Research team has received reports of a data stealing Trojan posing as a text document. Upon execution, the trojan downloads more malware onto the infected machine and also steals information from the system.

Infection Cycle:

The Trojan uses the following icon:

Figure 1: Trojan purports to be a Text document

It copies itself at the following location.

  • C:WINDOWSTempsample.exe – detected as GAV:MalAgent.H_4203 (Trojan)

The Trojan downloads 7qr.exe (which is a goodware but can be used in malicious campaigns).
The trojan injects into the Mozilla firefox:

It opens a firefox browser connecting to noticias.uol.com.br.

The malware contacts the following domains:

  • 74.63.197.237:80
  • 127.0.0.1:1032
  • conteudo2.uol.com.br:80 (200.147.68.19)
  • jsuol.com.br:80 (200.147.67.192)
  • stc.uol.com:443 (200.221.7.100)
  • e6845.dscb1.akamaiedge.net:80 (23.5.245.163)
  • cache.uol.com.br:80 (200.147.4.50)
  • 255.255.255.255:59981
  • tm.jsuol.com.br:80 (200.221.2.196)
  • cache.uol.com.br:80 (200.221.7.95)
  • jsuol.com.br:80 (200.221.2.85)
  • pix-geo.revsci.net:80 (64.94.116.164)
  • partnerad.l.doubleclick.net:80 (74.125.239.154)
  • thumb.mais.uol.com.br:80 (200.147.100.21)
  • tm.ipv6uol.com.br:443 (200.221.2.83)
  • partnerad.l.doubleclick.net:80 (74.125.239.141)
  • t5.dynad.net:80 (200.147.166.105)
  • d.tailtarget.com:80 (173.193.67.11)
  • pagead-googlehosted.l.google.com:80 (216.58.192.33)
  • adclient.siga.uol.com.br:80 (200.147.15.208)
  • uol.com.br.112.2o7.net:80 (66.235.139.152)
  • partnerad.l.doubleclick.net:443 (216.58.192.34)
  • a1294.w20.akamai.net:80 (205.169.30.211)
  • s.dynad.net:80 (200.147.166.107)

Once the 7z files are downloaded, it writes them to the C:DOCUME~1AdminLOCALS~1Temp folder and extracts them to C:compu92 using 7qr.exe.
The downloaded 7z file is encrypted and it is copied over to contains the following files:

The malware extracts Lb891b.cpl in the folder C:compu92. This modifies the user account settings with full access to modify the system.

Overall, this Trojan is capable of downloading additional malware into the victim’s machine. It can also send sensitive information out to a remote server.We urge our users to always be vigilant and cautious with any unsolicited attachments specially if you are not certain of the source.

Dell SonicWALL Gateway AntiVirus and Intrusion Prevention provides protection against this threat with the following signatures:

  • GAV:MalAgent.H_4203 (Trojan)