Backdoor.IRC.Cloner - Removal

Risk Level 1: Very Low

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Discovered: February 19, 2003
Updated: February 13, 2007 11:43:19 AM
Also Known As: Backdoor.IRC.Cloner [KAV], TROJ_CLONER.DRP [Trend], Backdoor:IRC/Cloner [RAV]
Type: Trojan Horse
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP


These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
  1. Update the virus definitions.
  2. Restart the computer in Safe mode.
  3. Run a full system scan and delete all the files detected as Backdoor.IRC.Cloner. Delete folders that the Trojan added.
  4. Delete the value that the Trojan added to the registry.

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

1. 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 the 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), in the "Protection" section, at the top of this writeup.
  • 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), in the "Protection" section, at the top of this writeup.

    The Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

2. Restarting the computer in Safe mode
All the Windows 32-bit operating systems, except Windows NT, can be restarted in Safe mode. For instructions on how to do this, read the document, "How to start the computer in Safe Mode."

3. 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.
  2. Run a full system scan.
  3. If any files are detected as infected with Backdoor.IRC.Cloner, write down the file name and location, and then click Delete.
  4. Using Windows Explorer, delete any subfolders added by the Trojan.

4. Deleting the value from the registry

CAUTION: Symantec strongly recommends that you back up the registry before you make 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 each of these keys:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
    CurrentVersion\RunServices
  4. In the right pane, delete the value that refers to the file that was detected as the Trojan.
  5. Exit the Registry Editor.


Writeup By: Atli Gudmundsson
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