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Bozori.B

Classification

Category: Malware

Type: -

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

Summary


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.

Removal


Automatic action

Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.

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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:

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"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		(Backdoor.Win32.IRCBot.es)		[uses MS05-039 exploit]
csm.exe		(Net-Worm.Win32.Mytob.cf / Zotob.B)	[uses MS05-039 exploit]
botzor.exe		(Net-Worm.Win32.Mytob.cd / 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]
service32.exe
llsrv.exe
system32.exe
Bot functionality

The backdoor connects to IRC server 72.20.41.139, 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