Published May 05, 2010 | Updated Sep 15, 2017


Severe |Detected with Windows Defender Antivirus

Aliases: Win-Trojan/Xema.variant (AhnLab) W32/EmailWorm.OXI (Command) Email-Worm.Win32.Brontok.q (Kaspersky) W32/Rontokbro (Norman) I-Worm.Brontok.QJ (VirusBuster) Worm/Brontok.FW (AVG) Worm/Brontok.C (Avira) Win32/Robknot.Z (CA) Win32/Brontok.S (ESET) Email-Worm.Win32.Brontok (Ikarus) W32/Rontokbro.gen@MM (McAfee) W32/Brontok.GS.WORM (Panda) Trojan.Win32.Mnless.dyr (Rising AV) W32/Brontok-G (Sophos) Email-Worm.Win32.Brontok.ik (Sunbelt Software) W32.Rontokbro@mm (Symantec) WORM_RONTOKBR.CO (Trend Micro)


Windows Defender  detects and removes this threat.
This threat is a mass-mailing worm that changes security systems on the infected computer. It usually arrives through spam e-mail.
It also modifies certain computer settings, such as how hidden files are displayed, and disables registry editing. It can also modify the computer's HOSTS file.
Manual removal is not recommended for this threat. Use the Microsoft Malicious Software Removal Tool, Microsoft Security Essentials, or another up-to-date scanning and removal tool to detect and remove this threat and other unwanted software from your computer. For more information on Microsoft security products, see
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 computers 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:
  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.
Enabling registry editor
This threat may modify the computer to prevent Registry Editor from running. To enable Registry Editor in your computer, please do the following:
  1. Run a command prompt. Click Start>Run and type cmd.
  2. In the command prompt, type the following as is and press Enter:
    reg.exe add HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System /v DisableRegistryTools /t REG_DWORD /d 0 /f
  3. Type exit at the command prompt.
Disabling Autorun functionality
Worm:Win32/Brontok.R@mm attempts to spread via removable drives on computers that support Autorun functionality. This is a particularly common method of spreading for many current malware families. For information on disabling Autorun functionality, please see the following article:
Additional remediation instructions for Worm:Win32/Brontok.R@mm
This threat may make lasting changes to a computer’s configuration that are NOT restored by detecting and removing this threat. For more information on returning an infected computer to its pre-infected state, please see the following article/s: 
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