W32/Sdbot-TO

Please follow the instructions for removing worms.

You will also need to edit the following registry entries, if they are present. Please read the warning about editing the registry.

At the taskbar, click Start|Run. Type 'Regedit' and press Return. The registry editor opens.

Before you edit the registry, you should make a backup. On the 'Registry' menu, click 'Export Registry File'. In the 'Export range' panel, click 'All', then save your registry as Backup.

Locate the HKEY_LOCAL_MACHINE entries:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices

and remove any reference to any file you deleted.

Each user has a registry area named HKEY_USERS\[code number indicating user]\. For each user locate the entry:

HKU\[code number]\Software\Microsoft\Windows\
CurrentVersion\Run\

and remove any reference to any file you deleted.

Close the registry editor.

W32/Sdbot-TO is a Windows worm that spreads via networks shares, drops files and contains backdoor functions that allow unauthorised remote access to the infected computer via IRC channels while running in the background.

When run the worm drops the files estem.exe (a component of itself) and tesnxm.exe into the C:\winnt\system32 folder and then proceeds to run both components.

tesnxm.exe is detected by Sophos as Troj/Ranck-BT.

The worm will also try to download and run files from the internet when instructed to do so by a remote attacker.

Sophos's anti-virus products include proactive protection technology, which can defend against new threats without requiring an update. Sophos customers have been protected against W32/Sdbot-TO (detected as W32/Sdbot-Fam) since version 3.89. W32/Sdbot-TO is a Windows worm that spreads via networks shares, drops files and contains backdoor functions that allow unauthorised remote access to the infected computer via IRC channels while running in the background.

When run the delivery component of the worm drops the files estem.exe (the worm core) and tesnxm.exe into the C:\winnt\system32 folder and then proceeds to run both files.

tesnxm.exe is detected by Sophos as Troj/Ranck-BT.

When estem.exe is executed it copies itself to the Windows system folder as uledit.exe.

The worm then creates the following registry entries so that it is able to run on user logon:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run
UltraEdit
uledit.exe

HKLM\Software\Microsoft\Windows\CurrentVersion\RunServices
UltraEdit
uledit.exe

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
UltraEdit
uledit.exe

W32/Sdbot-TO attempts to copy itself to network shares using the filename uldedit.exe.

The worm will also try to download and run files from the internet when instructed to do so by a remote attacker.

Sophos's anti-virus products include proactive protection technology, which can defend against new threats without requiring an update. Sophos customers have been protected against W32/Sdbot-TO (detected as W32/Sdbot-Fam) since version 3.89.