Microsoft security software detects and removes this threat.
Win32/Koobface is a multi-component family of malware used to compromise machines and direct them in various ways at the attacker's will.
This could include using the affected machine to distribute additional malware, generate 'pay per click' advertising revenue, steal sensitive data, break captchas, and subvert the affected user's online experience.
Its components are varied, but include a worm that spreads by utilizing social networking sites such as Facebook and MySpace.

What to do now

Use the following free Microsoft software to detect and remove this threat:

You should also run a full scan. A full scan might find other, hidden malware.

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.

Threat behavior


If this worm is executed, Win32/Koobface copies itself to the Windows folder as in the following examples:

  •  %windir%\fbtre6.exe
  • %windir%\mstre5.exe
  • %windir%\bolivar19.exe
  • %windir%\bolivar31.exe
  • %windir%\bolivar30.exe
  • %windir%\ld01.exe
  • %windir%\che08.exe
  • %windir%\freddy35.exe
The worm may drop a cleanup Batch script file also having a random file name to the root of the local drive, as in this example:
The worm may execute the cleanup batch script to remove the originally executed worm and to remove itself. The registry is modified to execute the dropped worm copy at each Windows start.
In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Sets value: systray
With data: "%windir%/<worm file name>"
Depending on the variant, other values are created instead such as "sysftray2" or "sysldtray".
Spreads through…
MySpace and FaceBook Contacts
Win32/Koobface searches in the default Internet Explorer cookies folder for browser cookies related to the Internet social network sites including the following:
In some variants of Win32/Koobface, if the worm determines that none of these sites are visited, the worm may delete itself and may display following message box:
In the wild, the worm may connect to the Web site '' to download and execute malware.
The worm spreads by sending messages containing a hyperlink to a copy of worm to friends or contacts of the infected user. Friends that receive the message may visit the link to download the worm and repeat the cycle of spreading to others.
Removes Audible Navigation Alerts
Some variants of Win32/Koobface may delete a registry subkey that references navigation sounds such as the 'click' sound when navigating from one Web site to another. The following subkey may be deleted by the worm:
Analysis by Vitaly Zaytsev


System Changes
The following system changes may indicate the presence of this malware:
  • The presence of the following files:
    • %windir%\bolivar19.exe
    • %windir%\bolivar31.exe
    • %windir%\bolivar30.exe
    • %windir%\ld01.exe
    • %windir%\che08.exe
    • %windir%\freddy35.exe

  • The display of the following messages:


Alert level: Severe
This entry was first published on: Mar 03, 2009
This entry was updated on: Aug 10, 2015

This threat is also detected as:
No known aliases