Threat Description



Aliases: SdBot, Backdoor.SdBot.gen, Randex.C, Slanper.A, Randex.C
Category: Malware
Platform: W32


Randex is an IRC controlled worm, based on the well known SdBot IRC backdoor. This worm infects Windows computers on local networks that use weak passwords.


Automatic action

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


Detailed instructions for F-Secure security products are available in the documentation found in 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.

Technical Details

Network spreading

Randex contains a list of passwords that it uses to get into poorly protected Windows accounts. The worm tries to connect to all windows computers with these passwords. If a password gives access to the computer Randex copies itself to the following places:

'\c$\winnt\system32\msmonk32.exe'  '\Admin$\system32\msmonk32.exe'  

When the files are in place the worm schedules a remote job to run itself on the remote computer.

Randex tries the following passwords:

"admin"  "root"  "1"  "111"  "123"  "1234"  "123456"  "654321"  "!@#$"  "asdf"  "asdfgh"  "!@#$%"  "!@#$%^"  "!@#$%^&"  "!@#$%^&*"  "server"  
System infection

When the worm is first run on a system it copies itself to the system directory with the name 'gesfm32.exe'. This copy of the worm is then added to the registry to the following locations:

'HKLM\Software\Microsoft\Windows\CurrentVersion\Run\Microsoft Netview'  'HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices\Microsoft Netview'  

To clean this worm these registry keys must be removed and the worm copies mentioned above deleted.

IRC controlled Backdoor

The backdoor component provides the usual set of functionality which is controlled through a predefined IRC channel.

By issuing commands on the control channel the remote attacker can:

- get info on the system  - set different parameters in the bot  - download arbitrary files to the computer  - execute programs on the computer  - etc.  

[F-Secure Corp.; June 23th, 2003]


Randex is detected by F-Secure Anti-Virus using generic detection as: Backdoor.SdBot.gen.


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