IRC.DMSetup.H

SUMMARY

The IRC.DMSetup.H worm uses the mIRC (Internet Relay Chat) program to spread.

Protection

• Virus Definitions (Intelligent Updater) January 3, 2001

Threat Assessment

Wild

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

Damage

• Damage Level: Low

Distribution

• Distribution Level: Medium
• Target of Infection: Win 95, Win 98, DOS

TECHNICAL DETAILS

This worm is a DOS-command-type executable file, with a .com extension. Its length is approximately 83 KB.

When activated, the worm runs in video mode. It takes over the whole screen and displays bubbles that change shape.

In the background, the worm does the following:

• Copies (or tries to copy) itself into the following locations:
  • C:WindowsLogox.sys
  • C:Windoom.exe
  • C:WindowsFreeporn.jpg.com
• Copies (or tries to copy) itself, with a randomly generated file name and the extension .jpg.com into the following locations:
  • C:
  • C:Windows
  • C:WindowsSystem
  • C:Mirc
  • C:Program Files
  • C:Codedbythecreator
  • C:Dos
  • C:Doom
  • C:Doom2
  • C:Quake
  • C:Games
  • C:Pics
• Deletes (or tries to delete) the Mircnew.exe file from the following locations:
  • C:
  • C:Windows
  • C:Mirc
• Deletes (or tries to delete) the Wincfg32.exe from the C:Windows folder.
• Creates C:Ni.cfg. This file contains the call to the copy of the worm.
• Replaces the content of the C:MircMirc.ini file. Sometimes, the worm will back up the contents of the original file to C:MircBackupwrks.ini.
• Creates the C:Mirc<random name>.ini file.
• Inserts the following lines into the Autoexec.bat file:
  
  copy c:windowslogox.sys c:windows<variable name>.jpg.com
  c:windows<variable name>.jpg.com -inauto

The newly created C:MircMirc.ini file contains settings that will force mIRC to read the C:Mirc<random name>.ini file each time the IRC connection is established. The <random name> file contains mIRC script. This script will be executed every time the file is read. The script contains commands to send the copy of the worm to the person with whom you are chatting.

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

To remove this worm:

1. Make sure that the worm is not running. If it is, press Ctrl+C to stop it.
2. Find and delete all of the copies of the worm mentioned in the Technical Description section.
3. Find and delete all the configuration and initialization files created by the worm, except for the Backupwrks.ini file. Rename this file to Mirc.ini.
4. Delete the following lines in the Autoexec.bat file:
   
   copy c:windowslogox.sys c:windows<variable name>.jpg.com
   
   c:windows<variable name>.jpg.com -inauto