W32/Sdbot-AFN

Please follow the instructions for removing worms.

W32/Sdbot-AFN is a worm and IRC backdoor for the Windows platform.

W32/Sdbot-AFN spreads to other network computers by exploiting common buffer overflow vulnerabilities, including:
LSASS (MS04-011), RPC-DCOM (MS04-012), PNP (MS05-039) and ASN.1 (MS04-007) and by copying itself to network shares protected by weak passwords.

W32/Sdbot-AFN runs continuously in the background, providing a backdoor server which allows a remote intruder to gain access and control over the computer via IRC channels.

W32/Sdbot-AFN includes functionality to access the internet and communicate with a remote server via HTTP.

When first run W32/Sdbot-AFN copies itself to <Windows system folder>\autoexec.exe.

The file autoexec.exe is registered as a new system driver service named "Workstations", with a display name of "lsass" and a startup type of automatic, so that it is started automatically during system startup. Registry
entries are created under:

HKLM\SYSTEM\CurrentControlSet\Services\Workstations\

W32/Sdbot-AFN sets the following registry entries, disabling the automatic startup of other software:

HKLM\SYSTEM\CurrentControlSet\Services\Messenger
Start
4

HKLM\SYSTEM\CurrentControlSet\Services\RemoteRegistry
Start
4

HKLM\SYSTEM\CurrentControlSet\Services\TlntSvr
Start
4

Registry entries are set as follows:

HKLM\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate
DoNotAllowXPSP2
1

HKLM\SOFTWARE\Microsoft\Ole
EnableDCOM
N

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
restrictanonymous
1

Registry entries are created under:

HKLM\SOFTWARE\Microsoft\Security Center\
HKLM\SOFTWARE\Policies\Microsoft\WindowsFirewall\DomainProfile\
HKLM\SOFTWARE\Policies\Microsoft\WindowsFirewall\StandardProfile\

The following patches for the operating system vulnerabilities exploited by W32/Sdbot-AFN are available from Microsoft:
MS04-007
MS04-011
MS04-012
MS05-039