Cobalt Strike Malware Threat Intel Advisory

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 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.

Tactics, Techniques, and Procedures

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