W32.HLLW.Gaobot.P

1. Copies itself as:
   • %System%\Svchosl.exe
   • %System%\Winhlpp32.exe
     
     NOTE: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
     
     
2. Adds the string value:
   
   "Config Loader"="svchosl.exe"
   
   to these registry keys:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
   RunServices
   
   so that the worm runs when you start Windows.
   
3. Creates the registry keys:
   
   HKEY_LOCAL_MACHINE\Software\MSSQLServer\Client\SuperSocketNetLib
   HKEY_LOCAL_MACHINE\Software\Microsoft\Client\SuperSocketNetLib
   
   and adds this string value to the keys:
   
   "ProtocolOrder"="tcp"
   
4. Creates the registry keys:
   
   HKEY_LOCAL_MACHINE\Software\MSSQLServer\Client\ConnectTo
   HKEY_LOCAL_MACHINE\Software\Microsoft\MSSQLServer\Client\ConnectTo
   
   and adds this string value to the key:
   
   "DSQUERY"="DBNETLIB"
   
5. Drops the file, %System%\Psexec.exe, which is 122,880 bytes in length. This is the Sysinternals remote execution utility.
   
6. Adds itself as a service with the name, "PSINFSVC" or "PsInfo Servic."
   
7. Opens a randomly changed TCP port to connect to the hacker.
   
8. Contains its own IRC client, allowing it to connect to an IRC channel that the worm predefines. Using the IRC channel, the worm listens for the commands from the hacker, who may perform any of the following actions:
   • Manages the installation of the worm
   • Dynamically updates the installed worm
   • Downloads and executes the files, which the hacker selects
   • Steals the compromised system information
   • Steals the CD-keys of some electronic games
   • Sends the worm to other IRC users
   • Launches flooding attacks
   • Opens/Closes the CD-ROM drive
   • Scans for and attempts to log in to the Microsoft SQL Servers
     
     
9. Probes the IPC$ shares using trivial user/password combinations. The worm uses Psexec.exe to copy itself as %Windir%\System32\Winhlpp32.exe to the shares and executes this copy in the remote computers. This action will only succeed if an open IPC$ exists.
   
   NOTE: %Windir% is a variable. The worm locates the Windows installation folder of the remote system and copies itself to the folder system32 under this location. By default, %Windir% is C:\Windows or C:\Winnt.
   
10. Creates a named Pipe \\.\pipe\psexecsvc and redirects the information from the pipe to the command psexec.exe.
    

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.