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Microsoft Security Intelligence
Published Nov 02, 2020 | Updated Dec 13, 2021

VirTool:Win64/CobaltStrike.A

Detected by Microsoft Defender Antivirus

Aliases: No associated aliases

Summary

Microsoft Defender Antivirus detects and removes this threat.

This threat represents a CobaltStrike Beacon payload associated with prior exploitation of the remote code execution vulnerability CVE-2021-44228 (also referred to as “Log4Shell”) in the Log4j component of Apache. This vulnerability affects Java-based applications that use Log4j 2 versions 2.0 through 2.14.1.

Attackers gain access to the target device and launch arbitrary remote code loaded from LDAP servers, which are logged and launched by the Log4j component. This can allow attackers to set up a CobaltStrike Beacon on a target, allowing for communication with and persistent access to the device.

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Microsoft Defender Antivirus  automatically removes threats as they are detected. If you have cloud-delivered protection, your device gets the latest defenses against new and unknown threats. If you don't have this feature enabled, update your antimalware definitions and run a full scan to remove this threat. You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

  • Confirm that this server has Apache and the Log4j component installed.
  • Check for possible post-exploitation activities, such as unusual behavior from users with elevated privileges or suspicious spawned processes. 
  • Stop suspicious processes, isolate affected devices, decommission compromised accounts or reset passwords, block IP addresses and URLs, and install security updates. Update the Log4j component to log4j-2.15.0 or ensure that the device is set to start with log4j2.formatMsgNoLookups set to True.
  • Contact your incident response team, or contact Microsoft support for investigation and remediation services

You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

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