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Published May 14, 2024 | Updated Feb 12, 2025

Backdoor:MSIL/CrimsonRat.A

Detected by Microsoft Defender Antivirus

Aliases: No associated aliases

Summary

CrimsonRAT is a remote access trojan that enables cybercriminals to modify or delete files and inject additional malware into the infected device, serving as a backdoor. 

For more details, read our Microsoft Security blog: Frequent freeloader part I: Secret Blizzard compromising Storm-0156 infrastructure for espionage | Microsoft Security Blog 

Microsoft Defender Antivirus automatically removes threats as they are detected. However, many infections can leave remnant files and system changes. Updating your antimalware definitions and running a full scan might help address these remnant artifacts.

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

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