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January 09, 2007

Trojan, Backdoor


Spybot.HS, a variant of Spybot, is a Trojan. Spybot.HS uses IRC networks to spread and has automatic updating capabilities. Spybot.HS steals certain information from an infected computer.

Disinfection & Removal

Automatic Disinfection

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.

Technical Details

Spybot.HS allows control of a victims' computer remotely by sending specific commands via IRC channels. This backdoor can also steal data, spread to the local network, and to computers vulnerable to exploits.

It drops the following file upon execution:

  • %Sysdir%\windows.exe - Copy of itself.

It will then pass the control over to the dropped file and delete itself after execution.

Spybot.HS also checks for the existence of the following mutex to ensure that there is only one instance of itself running in memory:

  • 1337bot

Spybot.HS adds these registry value launch points:

  • [HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices] InternetExplorer2 = %Sysdir%\windows.exe
  • [HKLM\Software\Microsoft\Windows\CurrentVersion\Run]InternetExplorer2=%Sysdir%\windows.exe

It also adds the following registry entry as part of its installation routine:

  • [HKEY_CURRENT_USER\Software\Microsoft\OLE] InternetExplorer2 = %Sysdir%\windows.exe

It also creates the following registry entry to allow itself to bypass the Windows Firewall:

  • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy \StandardProfile\AuthorizedApplications\List] %Sysdir%\windows.exe = "%Sysdir%\windows.exe:*:Enabled:InternetExplorer2"

Spybot.HS also connects to the following IRC server:

  • ircds.windowsantivirussystem.org:3132

It then joins the following IRC channel:

  • #nzm

Once connected, Spybot.HS awaits for commands from a remote user. It may perform the following backdoor operations:

  • Acquire system information
  • Download files from the Internet
  • Execute/Delete files
  • Perform IRC commands
  • Search for vulnerabilities
  • Terminate processes
  • Update itself

This backdoor may spread through local networks by taking advantage of the following vulnerabilities:

  • ASN.1 Vulnerability (MS04-007)
  • DCOM RPC Vulnerability (MS03-026) TCP port 135.
  • LSASS vulnerability (MS04-011) TCP port 445.
  • Microsoft Windows Server Service Remote Buffer Overflow Vulnerability (MS06-040)

Spybot.HS is packed with ASProtect 2.1 and ASPack 2.12

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