Backdoor.Way

SUMMARY

Backdoor.Way is a backdoor Trojan horse that allows unauthorized access to a compromised computer.

Protection

• Virus Definitions (Intelligent Updater) August 30, 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: Medium
• Payload Trigger: Running the Trojan
• Compromises Security Settings: Opens a port to allow the hacker access to the compromised computer.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When run, Backdoor.Way first makes several copies of itself in the following locations:

• \%System%Notepad.exe
• \%System%msgsvc.exe
  
  NOTE: %System% is a variable. The Trojan locates the System folder (by default, on a Windows 95/98/Me computer this is C:WindowsSystem) and copies itself to that location

These files are created with the "Hidden" and "System" attributes to hide them from you.

Next, in the registry key

HKEY_LOCAL_MACHINESoftware
Classes xtfileshellopencommand

it changes the Value data of the (Default) value from

C:WindowsNotepad.exe %1

to

C:WindowsSystemNotepad.exe %1

This ensures that the Trojan file Notepad.exe is run instead of the real Notepad program whenever you open a .txt file.

Finally, It adds the value

Msgtask     C:WindowsSystemmsgsvc.exe

to the key

HKEY_LOCAL_MACHINESoftwareMicrosoft
WindowsCurrentVersionRun

This ensures that the Trojan is run every time you start Windows.

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 all files that are detected as Backdoor.Way and remove the changes that it made to the registry.

To remove the Trojan:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and run a full system scan. Be sure that NAV is configured to scan all files.
3. Delete all files that are detected as Backdoor.Way

To edit the registry:

CAUTION: We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys specified. Please see the document How to back up the Windows registry before you proceed.

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 the key
   
   HKEY_LOCAL_MACHINESoftware
   Classes xtfileshellopencommand
   
4. In the right pane, double-click
   
   (Default)
   
   The Edit String dialog box appears.
   
5. Remove the text
   
   System
   
   from the line
   
   C:WindowsSystemNotepad.exe %1
   
   so that it is
   
   C:WindowsNotepad.exe %1
   
6. Navigate to the key
   
   HKEY_LOCAL_MACHINESoftwareMicrosoft
   WindowsCurrentVersionRun
   
7. In the right pane, select the value
   
   Msgtask C:WindowsSystemmsgsvc.exe
   
8. Press Delete, and then click Yes to confirm.
9. Exit the Registry Editor.