1. Symantec/
  2. Security Response/
  3. Backdoor.Sdbot


Risk Level 2: Low

April 30, 2002
February 13, 2007 11:39:02 AM
Also Known As:
IRC-Sdbot [McAfee], Backdoor.IRC.SdBot [Kaspersky], BKDR_SDBOT.B [Trend], Troj/Sdbot-B [Sophos], Win32.SdBot.14176 [CA]
Trojan Horse
Systems Affected:

When Backdoor.Sdbot is executed, it does the following:
  1. Copies itself to the %System% folder. The file name to which it copies itself can vary. Some known file names are:

    • Aim95.exe
    • CMagesta.exe
    • Cmd32.exe
    • Cnfgldr.exe
    • Explorer.exe
    • FB_PNU.EXE
    • MSTasks.exe
    • MSsrvs32.exe
    • Mssql.exe
    • Regrun.exe
    • Svchosts.exe
    • Sys32.exe
    • Sys3f2.exe
    • Syscfg32.exe
    • Sysmon16.exe
    • YahooMsgr.exe
    • cthelp.exe
    • iexplore.exe
    • ipcl32.exe
    • quicktimeprom.exe
    • service.exe
    • sock32.exe
    • spooler.exe
    • svhost.exe
    • syswin32.exe
    • vcvw.exe
    • winupdate32.exe
    • xmconfig.exe

      NOTE: %System% is a variable. The Trojan locates the \Windows\System folder (by default, this is C:\Windows\System or C:\Winnt\System32), and then copies itself to that location.

  2. Adds one of the following values:

    "Configuration Loader" = "%System%\iexplore.exe"
    "Configuration Loader" = "MSTasks.exe"
    "Configuration Loader" = "aim95.exe"
    "Configuration Loader" = "cmd32.exe"
    "Configuration Loader"= "IEXPL0RE.EXE"
    "Configuration Manager" = "Cnfgldr.exe"
    "Fixnice" = "vcvw.exe"
    "Internet Config" = "svchosts.exe"
    "Internet Protocol Configuration Loader" = "ipcl32.exe
    "MSSQL" = "Mssql.exe"
    "MachineTest" = "CMagesta.exe"
    "Microsoft Synchronization Manager" = "svhost.exe"
    "Microsoft Synchronization Manager" = "winupdate32.exe"
    "Microsoft Video Capture Controls" = "MSsrvs32.exe"
    "Quick Time file manager" = "quicktimeprom.exe"
    "Registry Checker" = "%System%\Regrun.exe"
    "Sock32" = "sock32.exe"
    "System Monitor" = "Sysmon16.exe"
    "System33" = "%System%\FB_PNU.EXE"
    "Windows Configuration" = "spooler.exe"
    "Windows Explorer" = " Explorer.exe"
    "Windows Services" = "service.exe"
    "Yahoo Instant Messenger" = "Yahoo Instant Messenger"
    "cthelp" = "cthelp.exe"
    "stratas" = "xmconfig.exe"
    "syswin32" = "syswin32.exe"

    or a similar value to the following registry subkeys:


  3. May create the following additional files:

    • %System%\SVKP.sys (This is a clean driver that can be used for malicious purposes.)
    • %System%\msdirectx.sys (This file is intended to provide rootkit functionality and may be detected as Hacktool.Rootkit.)

  4. Opens a back door by connecting to an IRC channel using its own IRC client. Some examples of IRC servers that it may connect to are:

    • bmu.h4x0rs.org
    • bmu.q8hell.org
    • bmu.FL0W1NG.NET

  5. Listens for the commands from a remote attacker. The attacker accesses the Trojan via IRC channels using a password-protected authorization. The remote attacker may perform the following actions on the compromised computer:

    • Manage the installation of the back door
    • Control the IRC client on a compromised computer
    • Dynamically update the Trojan
    • Send the Trojan to other IRC channels to attempt to compromise other computers
    • Download and execute files
    • Deliver system and network information to the attacker
    • Perform Denial of Service attacks against a third party
    • Completely uninstall itself by removing the relevant registry entries.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.
Writeup By: Serghei Sevcenco
Summary| Technical Details| Removal

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