Backdoor.Oblivion

SUMMARY

Backdoor.Oblivion is a Backdoor.Trojan that can allow unauthorized access to your computer.

Protection

• Virus Definitions (Intelligent Updater) October 23, 2001

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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When it is run, Backdoor.Oblivion copies itself as WindowsipLoader32.exe.

NOTE: ZipLoader32.exe is the most common file name, but it is not the only one. The file name can easily be changed by the hacker who is distributing the Trojan.

The Trojan then adds a reference to the dropped file in the following registry keys:

HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices

so that the Trojan runs when you start Windows.

It also may add a reference to the file in the System.ini and Win.ini files.

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 Trojan, delete files detected as Backdoor.Oblivion, and remove any values that it added to the registry, or references to it from the System.ini and Win.ini files.

To remove the Trojan:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
3. Run a full system scan.
4. Write down the file names of any files that are detected as Backdoor.Oblivion and then delete them.

To edit the registry:

CAUTION: We strongly recommend 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 only the keys that are specified. Read the document How to back up the Windows registry for instructions.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to each of the following keys:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices
   
4. In the right pane, look for lines that refer to the files, such as ZipLoader32.exe, that were detected as Backdoor.Oblivion, and delete any such values that you find.
5. Click Registry, and then click Exit.

To edit the System.ini and Win.ini files:
This needs to be done only on computers that are running Windows 95/98/Me.

NOTE: (For Windows Me users only) Due to the file-protection process in Windows Me, a backup copy of the file that you are about to edit exists in the C:WindowsRecent folder. We recommend that you delete this file before you continue with the steps in this section. To do this using Windows Explorer, go to C:WindowsRecent, and in the right pane select the Win.ini file and delete it. It will be regenerated as a copy of the file that you are about to edit when you save your changes to that file.

1. Click Start, and click Run.
2. Type the following, and then click OK.
   
   edit c:windowswin.ini
   
   The MS-DOS Editor opens.
   
   NOTE: If Windows is installed in a different location, make the appropriate path substitution.
   
3. In the [windows] section of the file, look for an entry similar to the following:
   
   load=<name of the file that was detected as ZipLoader32.exe>
   
4. Select the entire line. Be sure that you have not selected any other text; then press Delete.
5. In the [windows] section of the file, look for a line similar to the following:
   
   run=<name of the file that was detected as ZipLoader32.exe>
   
6. If it exists, select the entire line. Be sure that you do not select any other text; then press Delete.
7. Click File, and click Save.
8. Click File, and click Exit.
9. Click Start, and click Run.
10. Type the following, and then click OK.
    
    edit c:windowswin.ini
    
    The MS-DOS Editor opens.
    
    NOTE: If Windows is installed in a different location, make the appropriate path substitution.
    
11. In the [boot]section of the file, look for an entry that refers to the file that was detected as ZipLoader32.exe. Delete this reference.
    
    NOTE: If the reference is part of the line
    
    shell=explorer.exe
    
    delete only the text to the right of the .exe, so that, when you are done, this line reads only:
    
    shell=explorer.exe
    
12. Click File, and click Save.
13. Click File, and click Exit.