Cobalt Strike Malware Threat Intel Advisory

Published 31 December 2020


  • The new Muddy Water malware variant weaponizes Word documents embedded with macros
  • A Powershell script downloads legitimate image that contains a Cobalt Strike malware

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Advisory
Malware Intelligence
Potential Threat Actors
MuddyWater
Targeted Platform
Windows

 

The Iranian APT MuddyWater potentially uses a new strand of malware. The new variant weaponizes Word documents, embedded with malicious macros, that are sent to the victims as part of a phishing attack. The macros then launch a Powershell script that further downloads and x. The second Powershell script downloads a legitimate image that contains a Cobalt Strike malware encoded in the pixels of the image.

Malware Execution

When the malware is executed in the infected environment, it launches a Powershell script which further downloads a second Powershell script which is hosted on Github.

The Powershell script then downloads an image [PNG] from the image hosting platform Imgur.com, which hides an encoded Cobalt Strike payload in its pixels. After downloading the image the Powershell script decodes the payload which inturn enables the Cobalt Strike beacon to connect to the attackers’ infrastructure. Cobalt Strike masquerades as eicar, an anti-malware test file, to connect to the C2 server.

The account that holds the Powershell script on Github.

Powershell script on Github

 

Tactics, Techniques, and Procedures

Tactics
Techniques
Initial Access T1566.001 Phishing: Spear Phishing Attachment
Execution T1059.001 Command and Scripting Interpreter: PowerShell
Defense Evasion T1140 Deobfuscate/Decode Files or Information
T1027.003 Obfuscated Files or Information: Steganography
Command and Control T1001.002 Data Obfuscation: Steganography

 

Indicators of Compromise

  • d1c7a7511bd09b53c651f8ccc43e9c36ba80265ba11164f88d6863f0832d8f81
  • Ed93ce9f84dbea3c070b8e03b82b95eb0944c44c6444d967820a890e8218b866
  • Domain:Port : Mazzion1234-44451[.]portmap[.]host:44451
  • Url: hxxp://Mazzion1234-44451.portmap.host/fVRO

Impact

Technical Impact:
  • The malware is responsible of downloading Cobalt Strike malware
  • The malware can lead to further attacks on the victims
Business Impact:
  • Privacy violation
  • Victims are exposed to other attacks

Mitigation

  • Be careful with any attachment delivered by emails
  • Stay updated with latest patching
  • Apply effective application control policies

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