W32.HLLW.Raleka.B

SUMMARY

W32.HLLW.Raleka.B is a variant of W32.HLLW.Raleka that exploits the Microsoft DCOM RPC vulnerability, as described in Microsoft Security Bulletin MS03-026.

When W32.HLLW.Raleka.B is executed, it attempts to download the files from a predefined location and connect to an IRC server.

The worm is 33 Kb in size.

Protection

• Virus Definitions (LiveUpdate™ Weekly) January 21, 2004
• Virus Definitions (Intelligent Updater) January 19, 2004

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low
• Compromises Security Settings: Allows unauthorized execution of remote commands.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When W32.HLLW.Raleka.B is executed, it performs the following actions:

1. Attempts to download NTrootkit.exe and NTRootkit.reg from a predefined location. If successful, it will execute NTrootkit.exe.
   
   NTrootkit.exe is detected as Backdoor.Rtkit.
   
   
2. Launches a thread that attempts to connect to the following IRC servers on port 6667, one at a time, until a successful connection is made:
   
   • irc.servercentral.net
   • irc.secsup.org
   • irc.nac.net
   • irc.mpls.ca
   • irc.mindspring.com
   • irc.limelight.us
   • irc.isprime.com
   • irc.isdnet.fr
   • irc.ipv6.homelien.no
   • irc.inter.net.il
   • irc.inet.tele.dk
   • irc.homelien.no
   • irc.prison.net
   • irc.desync.com
   • irc.daxnet.no
   • irc.csbnet.se
   • irc.aol.com
   • irc.blessed.net
   • irc.banetele.no
   • irc.avalonworks.ca
   • irc.arcti.ca
   • irc.choopa.net
     
     
3. If the worm successfully connects to one of the servers, it will join a predefined chat channel.
   
   
4. May also receive various commands from the chat channel.
   
   
5. Once installed, the worm attempts to patch the system against the DCOM RPC vulnerability, by downloading the patch from download.microsoft.com.
   
   
6. Scans random IP addresses for other computers to exploit.
   
   
7. If the worm successfully exploits a remote computer, it opens a shell on that computer and creates the file Down.com.
   
   
8. Creates the log files, Rpcss.ini and Svchost.ini, and logs all the IP addresses it attempts to infect. The worm uses these files so that it does not attempt to infect the same IP range more than once.

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. Obtain the Microsoft patch to correct the DCOM RPC vulnerability.
2. Disable System Restore (Windows Me/XP).
3. Update the virus definitions.
4. Disconnect from any networks, including the Internet. Run a full system scan and delete all the files detected as W32.HLLW.Raleka.B.

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

1. Obtaining the Microsoft patch
Follow the instruction in Microsoft Security Bulletin MS03-026.

2. 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.

3. 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.

4. Scanning for and deleting the infected files

1. Disconnect the computer from all external sources. This includes local area networks and all internet connections.
2. 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."
3. Run a full system scan.
4. If any files are detected as infected with W32.HLLW.Raleka.B, click Delete.