Sophos

W32/Vanebot-K

Aliases
  • Backdoor.Win32.PcClient.qf
  • Win32/IRCBot.TB
Category
Type
What to do
Prevalence low high

Summary

 
How it spreads
  • Network shares
Affected operating systems Windows
Characteristics
  • Installs itself in the registry
Protection available since 7 September 2006 12:44:41 (GMT)
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Action

More Information

W32/Vanebot-K is a worm and IRC backdoor Trojan for the Windows platform.

W32/Vanebot-K attempts to spread via MSN Messenger, by copying itself to remote network shares with weak passwords and by exploiting any of the following vulnerabilities: SRVSVC (MS06-040), Psyme, PNP (MS05-039), ASN.1 (MS04-007).

W32/Vanebot-K 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/Vanebot-K copies itself to <System>\bootini.exe.

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

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Microsoft Windows
bootini.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Microsoft Windows
bootini.exe

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

HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Shell
Explorer.exe bootini.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/Vanebot-K 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,bootini.exe

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
lmcompatibilitylevel
1

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
restrictanonymous
1

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