Discovered: March 24, 2003
Updated: February 13, 2007 11:44:50 AM
Type: Trojan Horse
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows XP
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
- Update the virus definitions.
- Run a full system scan and delete all the files detected as Backdoor.Rsbot.
- Delete the value that was added to the registry.
- For Windows 95/98/Me, reverse the changes made to the System.ini file.
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 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 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. Scanning for and deleting the infected files
- Start your Symantec antivirus program and make sure that it is configured to scan all the files.
- Run a full system scan.
- If any files are detected as infected with Backdoor.Rsbot, click Delete.
3. 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.
- Click Start, and then click Run. (The Run dialog box appears.)
- Type regedit
Then click OK. (The Registry Editor opens.)
- Navigate to the key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- In the right pane, delete the value:
"WinApp32" = "msapp.exe"
- Exit the Registry Editor.
4. Reversing the changes made to the System.ini file
If you are running Windows 95/98/Me, follow these steps:
- The function you perform depends on your operating system:
- Windows 95/98: Go to step b.
- Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made a backup copy of the System.ini file that you need to edit. If this backup copy exists, it will be in the C:\Windows\Recent folder. Symantec recommends that you delete this file before continuing with the steps in this section. To do this:
- Start Windows Explorer.
- Browse to and select the C:\Windows\Recent folder.
- In the right pane, select the System.ini file and delete it. The System.ini file will be regenerated when you save your changes to it in step f.
- Click Start, and then click Run.
- Type the following:
edit c:\windows\system.ini
and then click OK. (The MS-DOS Editor opens.)
NOTE: If Windows is installed in a different location, make the appropriate path substitution.
- In the [boot] section of the file, look for a line similar to:
Shell=Explorer.exe msapp.exe
- If this line exists, delete everything to the right of Explorer.exe.
When you are done, it should look like:
shell=Explorer.exe
- Click File, and then click Save.
- Click File, and then click Exit.
Writeup By: Yana Liu