Trojan:Win64/Sirefef.AA is a user-mode component of the Sirefef malware family and runs on the 64-bit version of Windows. Sirefef is a multi-component family that performs different functions, such as downloading updates and additional Sirefef components, hiding existing Sirefef components or performing a payload. This malware moderates your Internet experience by changing search results, and generating pay-per-click advertising revenue for the malware controllers.

For more information about the Sirefef family, see the description for Win32/Sirefef elsewhere in the encyclopedia.

Trojan:Win64/Sirefef.AC is a component of Win64/Sirefef - a multi-component family of malware that uses stealth to hide its presence on your computer. The family consists of multiple parts that perform different functions, such as downloading updates and additional components, hiding existing components, or performing the payload.

Caution: Win64/Sirefef is a dangerous threat that uses advanced stealth techniques in order to hinder its detection and removal. As a consequence of being infected with this threat, you may need to repair and reconfigure some Windows security features. Please see Additional remediation steps in this entry for more information.

Trojan:Win64/Sirefef.AD is a component of Win64/Sirefef - a multi-component family of malware that moderates your Internet experience by changing search results and generating pay-per-click advertising revenue for its controllers. The family consists of multiple parts that perform different functions, such as downloading updates and additional components, hiding existing components, or performing a payload.

Trojan:Win64/Sirefef.K is the 64-bit user-mode component of Win32/Sirefef - a multi-component family of malware that moderates your Internet experience by changing search results and generating pay-per-click advertising revenue for its controllers. The family consists of multiple parts that perform different functions, such as downloading updates and additional components, hiding existing components, or performing a payload.

Trojan:Win64/Sirefef.C is a trojan that connects to a remote server to download arbitrary files which can include malware, such as other components of the Sirefef malware family. This trojan is commonly installed by another variant of Sirefef such as Trojan:Win32/Sirefef.J.