Digispid.B.Worm

When Digispid.B.Worm is executed on a vulnerable computer, it does the following:

It copies the following files to the hard disk:

• \System32\Drivers\Services.exe
  This is a port scanner that the worm uses to locate vulnerable computers.
• \System32\Sqlexec.js
  This is a JavaScript file that the worm uses to execute command-line functions on the remote computer.
• \System32\Clemail.exe
  This is a command-line email utility. The worm uses this program to send the IP address and SQL information in email to the virus writer.
• \System32\Sqlprocess.js
  This is a JavaScript file which performs the worm functionality. It does the following:
  
  It adds the values
  
  ImagePath  %COMSPEC% /c start netdde && sqlprocess init
  Start      2
  
  to the registry key
  
  HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NetDDE"
  
  It adds the value
  
  dsquery      dbmssocn
  
  to registry key
  
  HKEY_LOCAL_MACHINE\software\microsoft\mssqlserver\client\connectto
  
  It copies the file
  
  %SystemRoot%\System32\Regedt32.exe
  
  to
  
  %SystemRoot%\Regedt32.exe
  
  It deletes the file %SystemRoot%\System32\Msver241.srq
  
  The JavaScript sends the IP address and SQL table and row information to the virus writer. It also searches for vulnerable computers on networks whose IP addresses do not begin with 10, 127, 172, or 192. When it finds a vulnerable computer, it executes \System32\Sqlinstall.bat, which installs the worm onto the remote computer.
• \System32\Sqlinstall.bat
  This .bat file activates the guest user account, sets the guest user account password to a string of four random characters, and adds the guest account to the Administrators and Domain Admins groups.
  
  It then searches for the presence of \System32\Cscript.exe. If it finds the file, it then checks whether the worm has already copied the %SystemRoot%\System32\Regedt32.exe file to %SystemRoot%\Regedt32.exe. If so, the .bat file exits. Otherwise it copies the following files to the default system share of the remote computer:
  \System32\Drivers\Services.exe
  \System32\Sqlexec.js
  \System32\Clemail.exe
  \System32\Sqlprocess.js
  \System32\Sqlinstall.bat
  \System32\Sqldir.js
  \System32\Run.js
  \System32\Timer.dll
  \System32\Samdump.dll
  \System32\Pwdump2.exe
  
  After it copies these files, it changes the remote SQL administrator password to a string of four random characters. It then triggers the remote computer to execute Sqlprocess.js.
• \System32\Sqldir.js
  This is a JavaScript file which the worm uses to collect table and row information from the SQL Server.
• \System32\Run.js
  This is a JavaScript file which the worm uses to trigger the remote computers to execute the worm.
• \System32\Timer.dll
  This is a .dll file which the worm registers on the infected system. It is a simple timer program.
• \System32\Samdump.dll
  This is a .dll file that the worm copies to infected computers. It does not appear to perform malicious actions.
• \System32\Pwdump2.exe
  This is a file that the worm uses to attempt to steal the infected computer's password.

After the worm copies the preceding files, it changes the SQL administrator password to a string of four random characters.

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