Threat Description

Bozori.B

Details

Aliases: Bozori.B, Net-Worm.Win32.Bozori.b, W32.Zotob.F
Category: Malware
Type:
Platform: W32

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 Disinfection

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.



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






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