Threat Description



Aliases: Backdoor.Win32.IRCBot.ex
Category: Malware
Type: BackdoorWorm
Platform: W32


A remote administration utility that bypasses normal security mechanisms to secretly control a program, computer or network.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More scanning & removal options

More information on scanning or removal options is available in the documentation for your F-Secure security product on the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Eliminating a Local Network Outbreak

If the infection is in a local network, please follow the instructions on this webpage:

Technical Details

Backdoor:W32/IRCBot.EX provides unauthorised access to an infected computer and also has the capability to spread to remote computers using the PnP exploit on port 445.

The backdoor's file is a PE executable file about 8 kilobytes long, packed with MEW file compressor and patched with PE_Patch. The code of backdoor is encrypted with a simple cryptoalgorithm.

IRCBot.EX was found on August 17th, 2005 and is very similar to the IRCBot.ES variant found 2 days earlier.


The backdoor has the ability to spread to remote computers using the PnP exploit on port 445. Please see the following page for detailed information on the vulnerability:


When the backdoor's file is activated on a computer, it copies its file to Windows System folder as WPA.EXE and then starts the copied file as a service named 'Windows Product Activation', an "anti-piracy technology designed to verify that software products have been legitimately licensed".

If the backdoor fails to start its service, it tries to inject its code into Explorer.exe process.


When active, the backdoor connects to the following server on port 18067:


Then backdoor joins an IRC channel called '#p4' using the hardcoded password and creates a bot there. A remote hacker can control a backdoor via a bot that it creates in the '#p4' channel. A hacker can do any of the following:

  • Scan for vulnerable computers and spread to them using PnP exploit
  • Download and run files on an infected computer
  • Find files on local hard disks
  • Perform DDoS (Distributed Denial of Service) attack
  • Perform SYN and UDP flood


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