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Microsoft Security Intelligence
Published Mar 06, 2016 | Updated Jan 16, 2018


Detected by Microsoft Defender Antivirus

Aliases: Troj/Ransom-CJM (Sophos) Trojan.Cryptolocker.AH (Symantec)


Windows Defender detects and removes this threat.

This ransomware can stop you from using your PC or accessing your data.

It is a member of the ransomware-as-a-service category of ransomware, and spreads through email, exploit-kits, and other drive-by downloads. As of September, 2016, we have seen this threat use Exploit:HTML/Pangimop (Magnitude) and Exploit:HTML/Meadgive (Rig) exploit kits in its campaign in the Asian region (Taiwan and South Korea). We have also seen it distributed in email attachments that contain script-based downloaders, such as those written in javascript (.js), Office VBA (Word documents such as .doc and .rtf), and Windows Scripting File (.wsf). As of October 2016, we have seen Cerber delivered through password-protected email attachments, along with other threats.

It might ask you to pay money (in the form of bitcoins) to a malicious hacker. It can play a text-to-speech or synthesized recording, show a web page, or a plain text document. 

Our ransomware FAQ page has more information on this type of threat.

The trend towards increasingly sophisticated malware behavior, highlighted by the use of exploits and other attack vectors, makes older platforms so much more susceptible to ransomware attacks. From June to November 2017, Windows 7 devices were 3.4 times more likely to encounter ransomware compared to Windows 10 devices.

Read our latest report: A worthy upgrade: Next-gen security on Windows 10 proves resilient against ransomware outbreaks in 2017.



There is no one-size-fits-all response if you have been victimized by ransomware. There is no guarantee that paying the ransom will give you access to your files.

If you've already paid, see our ransomware page for help on what to do now.

Run antivirus or antimalware software

Use the following free Microsoft software to detect and remove this threat:

You should also run a full scan. A full scan might find hidden malware.

Use cloud protection

Use cloud protection to help guard against the latest malware threats. It’s turned on by default for Microsoft Security Essentials and Windows Defender for Windows 10. 

To check if it's running, go to All settings > Update & security > Windows Defender and make sure that your Cloud-based Protection settings is turned On.

Get more help

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

If you’re using Windows XP, see our Windows XP end of support page.

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