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Published Dec 24, 2009 | Updated Sep 15, 2017

Worm:Win32/Drefir.E

Detected by Microsoft Defender Antivirus

Aliases: W32/WormX.CX (Command) Win32.Worm.Drefir.E@MM (BitDefender) Win32.HLLM.Dref (Dr.Web) Win32/Drefir.E (ESET) Email-Worm.Win32.Drefir.l (Kaspersky) W32/Drefir.O@mm (Norman) W32/Drefir.E.worm (Panda) W32.Dref@mm (Symantec) WORM_DREFIR.C (Trend Micro) I-Worm.Drefir.E (VirusBuster)

Summary

Worm:Win32/Drefir.E is a worm that spreads by copying itself to mapped drives, by sending e-mail messages with an attached copy of the worm, and by sending messages in IRC channels containing a link to the worm. The worm lowers system security and may delete files on the 29th day of June and December.
Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as Microsoft Security Essentials, or the Microsoft Safety Scanner. For more information about using antivirus software, see http://www.microsoft.com/security/antivirus/av.aspx.
 
Recovering from recurring infections on a network
The following additional steps may need to be taken to completely remove this threat from an infected network, and to stop infections from recurring from this and other similar types of network-spreading malware:
 
  1. Ensure that an antivirus product is installed on ALL machines connected to the network that can access or host shares  (see above for further detail).
  2. Ensure that all available network shares are scanned with an up-to-date antivirus product.
  3. Restrict permissions as appropriate for network shares on your network. For more information on simple access control, please see: http://technet.microsoft.com/library/bb456977.aspx.
  4. Remove any unnecessary network shares or mapped drives.
 
Note: Additionally it may be necessary to temporarily change the permission on network shares to read-only until the disinfection process is complete.
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