W32/Kassbot-V

Please follow the instructions for removing worms.

W32/Kassbot-V is a worm and IRC backdoor Trojan for the Windows platform.

W32/Kassbot-V spreads to other network computers by exploiting common buffer overflow vulnerabilities, including: SRVSVC (MS06-040), Psyme, PNP (MS05-039) and ASN.1 (MS04-007) and by copying itself to network shares protected by weak passwords.

W32/Kassbot-V 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.

When first run W32/Kassbot-V copies itself to <System>\xpjavams.exe.

The following registry entries are created to run xpjavams.exe on startup:

HKCU\Software\Microsoft\Windows\CurrentVersion\RunServices
MS Java for Windows NT, XP & ME
xpjavams.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
MS Java for Windows NT, XP & ME
xpjavams.exe

The following registry entry is changed to run xpjavams.exe on startup:

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Shell
Explorer.exe xpjavams.exe

(the default value for this registry entry is "Explorer.exe" which causes the Microsoft file <Windows>\Explorer.exe to be run on startup).

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

HKLM\SYSTEM\CurrentControlSet\Services\wuauserv
Start
4

HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess
Start
4

Note: disabling autostart for the SharedAccess service deactivates the Microsoft Internet Connection Firewall (ICF).

Registry entries are set as follows:

HKLM\SOFTWARE\Microsoft\Ole
EnableDCOM
N

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Userinit
<System>\userinit.exe,xpjavams.exe

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
lmcompatibilitylevel
1

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
restrictanonymous
1