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Type :


Aliases :

Bozori.B, Net-Worm.Win32.Bozori.b, W32.Zotob.F


This IRC-based backdoor-worm was found on August 17th, 2005. The backdoor provides unauthorised access to an infected computer and also has the capability to spread to remote computers using the PNP exploit.


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

The executable is a file of around 10KB.

Installation to system

When the backdoor's file is activated on a computer, it copies its file to Windows System folder as 'wintbpx.exe' and then starts the copied file. Then it adds the following registry entries to ensure that it is started when a user logs on or the system is restarted:

"Wintbpx" = "wintbpx.exe"

Spreading using PnP exploit

The backdoor has the ability to spread to remote computers using the PNP exploit on port 445. If the attack is successful a shell (cmd.exe) is started on port 8563. Through the shell port, the worm sends a tftp script which instructs the remote computer to download and execute the worm from the attacker computer using built-in TFTP server listening on port 69.

Here's the summary of the ports used in attack:

  • Port 445- The worm scans for systems vulnerable to PnP exploit through this port
  • Port 69- TFTP server port on infected systems
  • Port 8563- The command shell port opened by the exploit code

Please see the following page for detailed information on the vulnerability:

Terminating processes

The backdoor tries to terminate and delete the files of the following processes:

wintbp.exe		(Net-Worm.Win32.Bozori.a)		[uses MS05-039 exploit]
winpnp.exe		(Backdoor.Win32.Rbot.ym)		[uses MS05-039 exploit]
mousebm.exe		(		[uses MS05-039 exploit]
csm.exe		( / Zotob.B)	[uses MS05-039 exploit]
botzor.exe		( / Zotob.A)	[uses MS05-039 exploit]
pnpsrv.exe		(Backdoor.Win32.Rbot.yk)		[uses MS05-039 exploit]
svnlitup32.exe		(Backdoor.Win32.SdBot.yx)		[uses MS05-039 exploit]
upnp.exe		(Backdoor.Win32.Codbot.ab)		[doesn't use MS05-039 exploit]

Bot functionality

The backdoor connects to IRC server, joins an IRC channel called '#tbp' and creates a bot there. The attacker can instruct the bot to execute the following actions:

Exit bot
Remove bot
Download and execute files from the Internet