Wave of Zortob Backdoor Trojan discovered in the wild (Oct 18, 2013)


The Dell SonicWall Threats Research team have received reports of a recent wave of the Zortob Trojan in the wild. Trojans of this nature may have no particular objective upon infection but give an attacker a back-door into the infected systems through which any other malware can be installed. This Trojan is reported to arrive as an email attachment masquerading as a voicemail message.

Infection cycle:

The Trojan uses the following icon to pose as a voicemail message:

The Trojan adds the following files to the filesystem:

  • %APPDATA%kqljentg.exe [Detected as GAV: Zortob.B_47 (Trojan)]
  • {run location}VoiceMail_Round_Rock_(512)4584934.txt

Once it is run it will delete itself and create VoiceMail_Round_Rock_(512)4584934.txt in the same location:

It will then open notepad.exe to display the text file:

The following IP addresses for C&C servers were discovered in the binary:


The following encrypted communication was observed between the Trojan and a remote C&C server:

During analysis we discovered the unencrypted form of the data sent above:

The response from the C&C server suggests that the Trojan remain idle. We also discovered various other commands in the Trojan binary:

  • idl
  • run
  • crc
  • rem
  • rdl
  • red
  • upd

SonicWALL Gateway AntiVirus provides protection against this threat via the following signatures:

  • GAV: Zortob.B_47 (Trojan)
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The SonicWall Capture Labs Threat Research Team gathers, analyzes and vets cross-vector threat information from the SonicWall Capture Threat network, consisting of global devices and resources, including more than 1 million security sensors in nearly 200 countries and territories. The research team identifies, analyzes, and mitigates critical vulnerabilities and malware daily through in-depth research, which drives protection for all SonicWall customers. In addition to safeguarding networks globally, the research team supports the larger threat intelligence community by releasing weekly deep technical analyses of the most critical threats to small businesses, providing critical knowledge that defenders need to protect their networks.