W32.Randex.T

SUMMARY

W32.Randex.T is a network-aware worm that copies itself as a self-extracting RAR file using one of the following file names:

• c$winntsystem32crsoss.exe
• c$winntsystem32vqmss.exe
  

The worm consists of three components:

• A self-extracting RAR file detected as W32.Randex.T
• The actual worm detected as W32.Randex.T
• A Trojan proxy detected as Backdoor.Ranck.C
  

The worm will receive instructions from an IRC channel on a specific IRC server. One such command will trigger the worm to spread.

Protection

• Virus Definitions (LiveUpdate™ Weekly) November 5, 2003
• Virus Definitions (Intelligent Updater) October 31, 2003

TECHNICAL DETAILS

W32.Randex.T arrives on an infected system as a self-extracting RAR file located in C:WinntSystem32.

When this file is executed, drops the following files to the %System% folder, and then executes them:

• The actual worm, which is detected as W32.Randex.T (37,888 bytes). The possible file names are EFQVB.EXE or QEVQEB.EXE.
  
• A Trojan proxy, which is detected as Backdoor.Ranck.C (24,064 bytes). The possible file names are EVVQS.EXE or GHJGRT.EXE.
  
  

When the worm component is executed, it does the following:

1. Copies itself as one of the following file names:
   
   • %System%Nvdes.exe
   • %System%Nvdas.exe
     
     NOTE: %System% is a variable. The worm locates the System folder and copies itself to that location. By default, this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
     
     
2. Adds one of the following string values:
   
   • "Postpatch"="nvdes.exe"
   • "Postdavatch"="nvdas.exe"
     
     to these registry keys:
     
   • HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   • HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersion
     RunServices
     
     so that the worm runs when you start Windows.
     
     
3. Calculates a random IP address for a computer to infect.
   
   
4. Copies the self-extracting RAR file to computers that have weak administrator passwords to:
   
   \<authenticated IP>c$winntsystem32
   
   using one of the following file names:
   
   • crsoss.exe
   • vqmss.exe
     
     
5. Remotely schedules a task to run the worm on a newly infected computer.
   
   
6. Connects to a specific IRC channel on a specific IRC server to receive remote instructions.
   
   
7. Steals the CD key of the following games:
   
   • Soldier of Fortune II - Double Helix
   • Neverwinter
   • WestwoodNox
   • Tiberian Sun
   • Red Alert 2
   • Red Alert
   • Project IGI 2
   • Command & Conquer Generals
   • Battlefield 1942 Secret Weapons of WWII
   • Battlefield 1942 The Road to Rome
   • Battlefield 1942
   • Rainbow Six III RavenShield
   • Nascar Racing 2003
   • Nascar Racing 2002
   • NHL 2003
   • NHL 2002
   • FIFA 2003
   • FIFA 2002
   • Need For Speed Hot Pursuit 2
   • The Gladiators
   • Unreal Tournament 2003
   • Legends of Might and Magic
   • Counter-Strike
   • Half-Life

Recommendations

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

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Restart the computer in Safe mode or VGA mode.
4. Run a full system scan and delete all the files detected as W32.Randex.T.
5. Delete the value that was added to the registry.
   

For specific details on each of these steps, read the following instructions.

1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

• "How to disable or enable Windows Me System Restore"
• "How to turn off or turn on Windows XP System Restore"

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.

2. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:

• Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
• Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).
  
  The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. Restarting the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.

• For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
• For Windows NT 4 users, restart the computer in VGA mode.

4. Scanning for and deleting the infected files

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan all files."
2. Run a full system scan.
3. If any files are detected as infected with W32.Randex.T, click Delete.

5. Deleting the value from the registry

CAUTION: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit
   
   Then click OK. (The Registry Editor opens.)
   
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete any of the following values:
   
   • "Postpatch"="nvdes.exe"
   • "Postdavatch"="nvdas.exe"
     
     
5. On Windows 95/98/Me computers, navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersion
   RunServices
   
   
6. In the right pane, delete any of the following values:
   
   • "Postpatch"="nvdes.exe"
   • "Postdavatch"="nvdas.exe"
     
     
7. Exit the Registry Editor.