Published Mar 16, 2012|Updated Sep 15, 2017


Severe |Detected with Windows Defender Antivirus

Aliases: Backdoor/Win32.ZAccess (AhnLab) BackDoor.Maxplus.90 (Dr.Web) Win32/Sirefef.DL trojan (ESET) Backdoor.Win32.ZAccess (Ikarus) Backdoor.Win32.ZAccess.aug (Kaspersky) Mal/Sirefef-AA (Sophos) BKDR_ZACCESS.FP (Trend Micro)


Microsoft security software detects and removes this threat.

This family of malware uses stealth to hide itself. Trojans in this family can do different things, including:

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

Members of the family can also change search results, which can generate money for the attackers who use Sirefef.

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

See the Win32/Sirefef family description for more information.


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