Fake Twitter spam – Merond Worm (Oct 2, 2009)


SonicWALL UTM Research team observed a new Merond worm variant being spammed in the wild via fake Twitter invitation e-mail messages. The e-mail message looks like below:

Sender: invitations@twitter.com [Spoofed sender address]

Subject: Your friend invited you to twitter!

Attachment: Invitation Card.zip [ Contains document.doc (spaces) .exe ]

The malicious executable inside the attachment is the new mass-mailing worm variant and the file looks like:


A sample e-mail message is shown below:


The worm when executed performs following activities on victim machine:

  • Injects a malicious executable into multiple system files on the victim machine some of which are listed below:
    • (System Folder)attrib.exe
    • (System Folder)bootcfg.exe
    • (System Folder)calc.exe
    • (System Folder)chkdsk.exe
  • Determines the IP address of the victim machine by sending a GET request to whatismyip.com
  • Emails copy of itself to the e-mail addresses harvested from the victim machine
  • Collects and sends back sensitive information from the victim machine to the predetermined IP address on port 65520. A sample encrypted packet is shown below:


  • Downloads rogueware applications on victim machine.

This malware is also known as TR/Buzus.caro [AntiVir], Worm:Win32/Prolaco.gen!C [Microsoft], and Worm:W32/Prolaco.D [F-Secure].

SonicWALL Gateway AntiVirus provides protection against this malware via GAV: Merond.V (Worm) signature.

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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.