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Aliases :

Rbot.xt, Backdoor.Win32.Rbot.xt, Rbot


RBot represents the large family of backdoors - hacker's remote access tools. These tools allow to contol victims' computers remotely by sending specific commands via IRC channels. Also, these backdoors can steal data and spread to computers vulnerable to exploits.


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

When the backdoor's file is started, it copies itself as 'MSDOS.PIF' file to Windows System folder and then creates the following startup key values in the Registry:

"MSDOS Windows Service" = "MSDOS.PIF"
"MSDOS Windows Service" = "MSDOS.PIF"
"MSDOS Windows Service" = "MSDOS.PIF"

When the backdoor is active, it connects to an IRC server, joins a certain channel and acts as a bot there. The backdoor also starts IDENTD server on port 113.

The following IRC server and ports is used by the backdoor:

The backdoor joins the following password-protected IRC channel:


A hacker can send commands to the bots to control infected computers. Several tasks can be performed, including the following:

* start FTP server
* start TFTP server
* perform ping, SYN, ICMP and UDP flood
* get system information including information about OS, network and drives
* update the backdoor's file from Internet
* operate backdoor's bot (nick change, join/part channels, etc.)
* start remote shell (cmd.exe)
* download and execute files
* enumerate remote shares
* scan and exploit computers vulnerable to exploits

When spreading, the bot can exploit the following vulnerabilities:

* RPC DCOM (MS03-026) ports 135, 445
* WKSSVC (MS03-049) ports 135, 445

The bot also tries to connect to IPC$ share, ports 135, 139 and 445 with administrator account and drop a copy of itself in the following directories: