Threat description




SdBot represents the large family of backdoors - hacker's remote access tools.


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

You can refer to General Removal Instructions for a simple guide on how to remove harmful programs.

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

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

Network Disinfection

For general instructions on disinfecting a local network infection, please see Eliminating A Local Network Outbreak.

Manual Disinfection

Caution: Manual disinfection is a risky process; it is recommended only for advanced users.

Manual disinfection for SdBot.ADA backdoor requires renaming of an infected file named WINLOGON.PIF located in Windows System folder and restarting a system. Please note that the backdoor's file has read-only, system and hidden attributes, so Windows Explorer has to be configured to show such files.

Technical Details

These tools allow to control victims' computers remotely by sending specific commands via IRC channels. Also these backdoors can steal data, spread to local network and to computers vulnerable to exploits.

This SDBot variant was first found on August 11th, 2005. It uses different exploits to spread to vulnerable computers.

The backdoor's file is a compressed PE executable about 146 kilobytes long, the unpacked file's size is over 340 kilobytes.

When the backdoor's file is started, it copies itself as WINLOGON.PIF to Windows System folder, sets hidden, system and read-only attributes for itself and then creates the following startup keys in the Registry:

  • [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run] "Windows Logon Service"="winlogon.pif"
  • [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunServices] "Windows Logon Service"="winlogon.pif"
  • [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run] "Windows Logon Service"="winlogon.pif"
  • [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices] "Windows Logon Service"="winlogon.pif"

The backdoor can scan for vulnerable computers using different types of exploits. Here's the list of scanner capabilities:

  • DCOM RPC (ports 139 and 445)
  • NTPass (ports 135, 139 and 445)
  • WKSSVC (ports 135 and 445)

A hacker can control the backdoor via a bot that it creates in a certain IRC channel. Backdoor capabilities are the following:

  • start an FTP server on an infected computer
  • scan for vulnerable computers (open ports and exploits)
  • operate backdoor's bot (nick change, join/part channels, etc.)
  • perform DDoS (Distributed Denial of Service) attack, SYN, ICMP, UDP flood
  • make use of exploits and spread to remote computers (also via IM)
  • get system information including information about OS, network and drives
  • update the backdoor's file from Internet
  • download and run files from Internet
  • delete or create network shares
  • start, stop and pause services
  • list, start and kill threads
  • start remote command shell
  • change security settings
  • flush DNS cache
  • ping any host

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