W32/Tilebot-KS

Please follow the instructions for removing worms.

W32/Tilebot-KS is a worm for the Windows platform.

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

W32/Tilebot-KS 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/Tilebot-KS includes functionality to:

- set up an FTP server
- set up a proxy server
- spread via MSN Instant Messager by sending messages automatically
- change Internet Explorer start page
- set or remove network shares
- port scanning
- packet sniffing
- start a remote shell (RLOGIN)
- access the internet and communicate with a remote server via HTTP

When first run W32/Tilebot-KS copies itself to <Windows>\schedhlp.exe.

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

HKLM\SYSTEM\CurrentControlSet\Services\Acronis Scheduler_Helper

W32/Tilebot-KS attempts to disable the system file checker by modifying sfc_os.dll or sfc.dll and setting the following registry entries:

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
SFCScan
0

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
SFCDisable
ffffff9d

The modified sfc_os.dll or sfc.dll is detected as "Disabled System File Check DLL".

W32/Tilebot-KS replaces the following files with programs that do nothing:

<System>\ftp.exe
<System>\tftp.exe

The original versions of ftp.exe and tftp.exe are copied to:

<System>\Microsoft\backup.ftp
<System>\Microsoft\backup.tftp

The worm may modify the following file:

<System>\Drivers\tcpip.sys

The following registry entries are set, disabling system software:

HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System
DisableTaskMgr
1

HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System
DisableRegistryTools
1

W32/Tilebot-KS 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\Microsoft\Windows NT\CurrentVersion\Winlogon
SFCScan
0

HKLM\SOFTWARE\Policies\Microsoft\WindowsFirewall\DomainProfile
EnableFirewall
0

HKLM\SOFTWARE\Policies\Microsoft\WindowsFirewall\StandardProfile
EnableFirewall
0

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

HKLM\SOFTWARE\Microsoft\Ole
EnableDCOM
N

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Shell
Explorer.exe %WINDIR%\schedhlp.exe

Registry entries are created under:

HKLM\SOFTWARE\Microsoft\Security Center
HKLM\SOFTWARE\Symantec\LiveUpdate Admin