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Published Apr 12, 2012 | Updated Sep 15, 2017

Trojan:Win32/Sirefef

Detected with Windows Defender Antivirus

Aliases: ZeroAccess (other) Zero Access (other)

Summary

Microsoft security software detects and removes this threat.

This threat is a member of the Win32/Sefnit family. This family can hide on your PC and do different things, including:

  • Downloading and running other files
  • Contacting remote hosts
  • Disabling security features

They can also change your search results, which can generate money for malicious hackers.

Variants of Win32/Sirefef might be installed by other malware, including variants of the Trojan:Win32/Necurs family.

The following free Microsoft software detects and removes this threat:

Even if we've already detected and removed this particular threat, running a full scan might find other malware that is hiding on your PC.

Restore your settings

Note that as part of the cleaning, our software might change some Windows services back to their default settings. If you had previously changed these settings, you might need to change them again.

The services that are reset include:

  • BFE – Base Filtering Engine
  • Iphlsvc – IP helper Service
  • MSMpSvc – Microsoft Antimalware service – MSE/FEP/SCEP
  • Sharedaccess – Internet Connection Sharing
  • WinDefend – Microsoft Antimalware service
  • Wscsvc - Windows Security Center
Advanced troubleshooting

To restore your PC, you might need to download and run Windows Defender Offline. See our advanced troubleshooting page for more help.

You can also ask for help from other PC users at the Microsoft virus and malware community.

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

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