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Aliases :

SdBot, Backdoor.SdBot.gen, Randex.C, Slanper.A, Randex.C


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.


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

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:


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

Randex tries the following passwords:


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.