Threat Description

Backdoor: W32/SdBot.AAY


Category: Malware
Type: Backdoor
Platform: W32
Aliases: Backdoor:W32/SdBot.AAY, Backdoor.Win32.SdBot.aay


A remote administration utility which 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 more information.

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

Backdoor:W32/SdBot.AAY spreads by exploiting a variety of vulnerabilities and can be controlled by a remote attacker through a password-protected IRC channel.

The backdoor's file is a PE executable about 210 kilobytes long, packed with SVPK file compressor.


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

  • "Shell" = "Explorer.exe mssvces.exe"

The bot exploits the following vulnerabilities in order to spread:

  • LSASS (MS04-011) port 445
  • WKSSVC (MS03-049) port 445
  • ASN.1 (MS04-007) ports 80, 139, 445

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 are used by the backdoor:


The backdoor joins the following password-protected IRC channel:

  • #asnpwn

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

  • start FTP 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.)
  • redirect traffic on certain ports
  • open a URL with default web browser
  • join and spy on certain IRC channels
  • download and execute files
  • manipulate Internet Explorer zone settings
  • scan and exploit computers vulnerable to exploits


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