We're gradually updating threat actor names in our reports to align with the new weather-themed taxonomy. Learn about Microsoft threat actor names
Trojan:Win32/Sirefef.AN
Aliases: Backdoor.Win32.ZAccess.tyi (Kaspersky) Mal/ZAccess-CA (Sophos) TR/ATRAPS.Gen2 (Avira) TROJ_SIREFEF.CZ (Trend Micro) Trojan.Win32.Alureon (Ikarus) ZeroAccess (McAfee)
Summary
Microsoft security software detects and removes this threat.
This threat is a member of the Win32/Sirefef family. Trojans in this family can do different things, including:
- Changing your search results
- Downloading and running other files
- Contacting remote hosts
- Disabling security features
Sirefef variants can be installed by other malware, including members of the Trojan:Win32/Necurs family.
The following free Microsoft software detects and removes this threat:
- Microsoft Defender Antivirus for Windows 10 and Windows 8.1, or Microsoft Security Essentials for Windows 7 and Windows Vista
- Microsoft Safety Scanner
- Microsoft Windows Malicious Software Removal Tool
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.
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.
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
Get more help
You can also visit our advanced troubleshooting page 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.
