W32.Cycle

1. Creates the following files:
   • %Windir%\cyclone.txt
   • %Windir%\system\svchost.exe (a copy of the worm)
     
     

     ---

     Note: %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.

     ---

     
     
2. Ends the following processes:
   • msblast.exe
   • avserve.exe
   • avserve2.exe
   • skynetave.exe
     
     
3. Creates the following mutexes:
   • SkynetSasserVersionWithPingFast
   • Jobaka3l
   • JumpallsNlsTillt
   • Jobaka3
     
     
4. If the system clock's date is set to May 18, it will perform Denial of Service (DoS) attacks against www.irna.com and www.bbcnews.com.
   
   
5. Listens on TCP port 3332. This open port is used as an infection marker. The worm will accept connections on this port and immediately close them. This notifies other instances of the worm that the computer is already infected.
   
   
6. Runs a TFTP server on UDP port 69, which will send a copy of the worm to the processes connecting to that port.
   
   
7. Generates a random IP address and attempts to connect to TCP port 445 on any computer at the IP address.
   
   As part of the infection routine, it tries to connect to TCP port 3332 on the remote computer. If the connection is made, it is assumed that the computer is already infected and the infection attempt is ended.
   
   
8. Runs a remote shell, which downloads a copy of the worm from the TFTP server on UDP port 69, and then runs it. This requires that there is a TFTP client named "tftp" in the path of the computer, on which the remote shell runs.
   
   The name of the downloaded file is cyclone.exe.
   
   
9. When the downloaded file runs, it may modify the value:
   
   "Generic Host Service"="%windir%\system\svchost.exe"
   
   in the registry keys:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

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.