Win32/Sirefef [Threat Name] go to Threat

Win32/Sirefef.EV [Threat Variant Name]

Available cleaner [Download Sirefef Cleaner ]

Category trojan
Size 169472 B
Aliases Trojan:Win32/Sirefef.P (Microsoft)
  BDS/ZAccess.yug (Avira) (McAfee)
Short description

The trojan serves as a backdoor. It can be controlled remotely.


When executed, the trojan creates the following files:

  • %recyclebin%\­%userSID%\­%variable%\­n (47616 B)
  • %recyclebin%\­%userSID%\­%variable%\­@ (2048 B)

The trojan creates the following folders:

  • %recyclebin%\­%userSID%\­%variable%\­U
  • %recyclebin%\­%userSID%\­%variable%\­L

A string with variable content is used instead of %variable% .

In order to be executed on every system start, the trojan sets the following Registry entries:

  • [HKEY_CURRENT_USER\­Software\­Classes\­clsid\­{fbeb8a05-beee-4442-804e-409d6c4515e9}\­InprocServer32]
    • "ThreadingModel" = "Both"
    • “(Default)" = "%recyclebin%\­%userSID%\­%variable%\­n."
  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­Classes\­CLSID\­{5839FCA9-774D-42A1-ACDA-D6A79037F57F}\­InprocServer32]
    • “(Default)" = "%recyclebin%\­S-1-5-18\­%variable%\­n."
    • "ThreadingModel" = "Free"

The following Registry entries are removed:

  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­Microsoft\­Windows\­CurrentVersion\­explorer\­ShellServiceObjects\­{FD6905CE-952F-41F1-9A6F-135D9C6622CC}]
  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­Microsoft\­Windows\­CurrentVersion\­explorer\­ShellServiceObjects\­{F56F6FDD-AA9D-4618-A949-C1B91AF43B1A}]
  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­Microsoft\­Windows\­CurrentVersion\­Run]
    • "Windows Defender"

The trojan loads and injects the "n" library into the following processes:

  • explorer.exe
  • services.exe

After the installation is complete, the trojan deletes the original executable file.

Other information

The trojan serves as a backdoor. It can be controlled remotely.

The trojan opens 16464 port and connects to own peer-to-peer network.

The trojan contains a list of (256) IP addresses.

It can execute the following operations:

  • download files from a remote computer and/or the Internet
  • run executable files
  • terminate running processes
  • open ports

The following programs are terminated:

  • wscntfy.exe
  • MSASCui.exe
  • MpCmdRun.exe
  • NisSrv.exe
  • msseces.exe

The following services are disabled:

  • MsMpSvc
  • windefend
  • SharedAccess
  • iphlpsvc
  • wscsvc
  • mpssvc
  • bfe

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