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Published Apr 14, 2005 | Updated Sep 15, 2017

Worm:Win32/Mytob.Z@mm

Detected by Microsoft Defender Antivirus

Aliases: Win32/Mytob.worm.Gen (AhnLab) W32/Mytob.au@MM (Command) Generic3.EOB (AVG) Win32.Worm.Mytob.AB.Damaged (BitDefender) Win32/Mytob.AD (ESET) W32/Mytob.ab@MM (McAfee) W32/Mytob.AI (Norman) W32/Mytob-AB (Sophos) Mytob.ab (Sunbelt Software) W32.Mytob.AF@mm (Symantec) WORM_MYTOB.AM (Trend Micro) I-Worm.Mytob.AJ (VirusBuster)

Summary

Win32/Mytob.Z@mm is a mass mailing worm that targets certain versions of Windows. It spreads to other computers by exploiting Windows vulnerabilities, and through MSN or Windows messenger. The worm also functions as an Internet Relay Chat (IRC) client 'bot' to receive commands from attackers.
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 the Microsoft Safety Scanner (http://go.microsoft.com/fwlink/?LinkId=212742). For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.
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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