W32.Choke.Worm

This worm spreads itself as the file ShootPresidentBUSH.exe.

When executed, the worm does the following:

1. It becomes memory resident.
2. It creates the following files:
   • C:\Choke.exe (a copy of the worm).
   • C:\ShootPresidentBUSH.exe (a copy of the worm).
   • C:\About.txt (contains surrealistic expressions from the author).
   • C:\Dalist.txt (contains list of buddies that have already been given a copy of the worm).
3. It then displays the following messages:
   
   
   
   and
   
   
   
4. After you click OK to these messages, you will not see any other output from this program. This could cause you to believe that the worm has terminated execution, when in fact it is still running on the system.

The worm hooks MSNMS in such away that when a buddy initiates a text conversation (for the first time) with an infected system, it sends the text message

President bush shooter is game that allows you to shoot Bush balzz  hahaha

along with an invitation to download a file named ShootPresidentBUSH.exe. If the buddy declines, the worm will not take no for an answer, and tries repeatedly until the buddy accepts the invitation.

The worm remembers the names of the buddies who have already been sent a copy of it, and responds with a smiley face to every line typed by that person.

The worm may, under some conditions, create a value in the registry key

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run

that references either of the executable files that it created on drive C.

This worm contains many bugs and may eventually cause the system to stop responding.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
• Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
• Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
• Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
• Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
• Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
• If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
• Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
• Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
• If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
• For further information on the terms used in this document, please refer to the Security Response glossary.

Summary