Threat Descriptons



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This type of trojan secretly downloads malicious files from a remote server, then installs and executes the files.


Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

This trojan is designed to promote rogue security applications by alarming users into believing that their system is infected with spyware. The user is then encouraged to purchase these rogue security applications, which are available from a variety of mirror sites.


Upon installation, the trojan drops the following two files on the system:

  • Trojan-Downloader:W32/FakeAlert.BG is dropped in %WINDOWS%/system32/brastk.exe
  • Rootkit:W32/AVKill.gen is dropped in %WINDOWS%\\dllcache\\figaro.sys

It will also replace the original file %WINDOWS%/system32/drivers/beep.sys with a malicious rootkit, %WINDOWS%\\dllcache\\figaro.sys.

The malware is designed to alarm the user into thinking their system is infected. To do so, the malware modifies some registry keys, then reboots the system to activate both the rootkit and its own executable. After system reboot, the user will occasionally see the following message appear in a system tray message balloon:

  • "Your computer is infected! Windows has detected spyware infection! It is recommended to use special antispyware tools to prevent data loss. Windows will now download and install the most up-to-date antispyware for you. Click here to protect your computer from spyware!"

If the user clicks on the message, they will be further cajoled into paying for a rogue security application.


The rootkit protects the malware and prevents users from seeing the brastk.exe process by hooking a Windows kernel function. The rootkit will also protects itself from a large number of programs which might detect and remove it - in particular antispyware and antivirus security applications - by preventing these programs from running. These programs include:

  • avgagent.exe
  • avgemc.exe
  • avpcc.exe
  • avp.exe
  • avpm.exe
  • avsched32.exe
  • eyetidecontroller.exe
  • f-sched.exe
  • f-stopw.exe
  • farsighter.exe
  • fatbuster.exe
  • fsav32.exe
  • kavss.exe
  • kavsvc.exe
  • klpf.exe
  • klswd.exe
  • kpf4ss.exe
  • little_helper2.exe
  • livesrv.exe
  • lsasrv.exe
  • lsass32.exe
  • magiclink.exe
  • malscr.exe
  • malswep.exe
  • njexplor.exe
  • nlsupervisorpro.exe
  • no32mon.exe
  • nod32krn.exe
  • nod32ra.exe
  • nortonupdate.exe
  • pboptions.exe
  • rtvscan.exe
  • sandboxieserver.exe
  • savscan.exe
  • spybot.exe
  • spybotsd.exe
  • spywaredetector.exe
  • zclient.exe
  • zcodec.exe
  • zcomservice.exe
  • sdfix.exe
  • ccpwdsvc.exe
  • ccsetmgr.exe
  • defwatch.exe
  • combo.exe
  • procmast.exe
  • dss.exe
  • globkill.exe
  • navapsvc.exe
  • navilog
  • prevxcsi.exe
  • fwservice.exe
  • savscan.exe
  • symlcsvc.exe
  • avgas.exe
  • prevxcsi.exe
  • avgw.exe
  • avgamsvr.exe
  • avgupsvc.exe
  • killbox.exe
  • gmer.exe
  • aluschedulersvc.exe
  • appsvc32.exe
  • apvxdwin.exe
  • ashmaisv.exe
  • ashserv.exe
  • ashwebsv.exe
  • avciman.exe
  • avengine.exe
  • avgas.exe
  • avgemc.exe
  • avgupsvc.exe
  • avgw.exe
  • pavprsrv.exe
  • ndmon.exe
  • sndsrvc.exe
  • spbbcsvc.exe
  • spyblock.dll
  • superantispyware.exe
  • svcntaux.exe
  • swdsvc.exe
  • symlcsvc.exe
  • symwsc.exe
  • thguard.exe
  • tpsrv.exe
  • trjscan.exe
  • vundofix.exe
  • autoruns.exe
  • rootkit_detektive.exe
  • winavxx.exe
  • kmd.exe
  • vsdatant.sys
  • watchdog.sys
  • bcfilter.sys
  • bcftdi.sys
  • bc_hassh_f.sys

Network Connections

Attempts to download files from:


Registry Modifications

Sets these values:

  • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run brastk = C:\WINDOWS\System32\brastk.exe
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