Backdoor.OptixPro.11

SUMMARY

Backdoor.OptixPro.11 is a backdoor Trojan that gives an attacker unauthorized access to an infected computer. By default it opens port 50021 on the compromised computer. Backdoor.OptixPro.11 is a Delphi application and is packed with tElock v0.98. It copies itself as %windir%Win32loader.exe.

Protection

• Virus Definitions (LiveUpdate™ Weekly) September 25, 2002
• Virus Definitions (Intelligent Updater) September 24, 2002

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
• Modifies Files: Modifies system registry.
• Releases Confidential Info: Intercept confidential information by hooking any keystrokes.
• Compromises Security Settings: Allows unauthorized access to the compromised machine. Attempts to disables some antivirus and firewall programs by terminating the active processes.

Distribution

• Distribution Level: Low
• Ports: 50021

TECHNICAL DETAILS

Backdoor.OptixPro.11 is similar in functionality to Backdoor.OptixPro.10. When Backdoor.OptixPro.11 runs, it performs the following actions:

It displays the message "General Protection Fault at address 0x00000004."

It copies itself as %windir%Win32loader.exe.

It drops the file %windir%Wmmiexe.exe. (This file is detected by Symantec antivirus product as Backdoor.Optix.)

NOTE: %windir% is a variable. The Trojan locates the primary Windows installation folder (by default this is C:Windows or C:Winnt) and uses it as a destination folder.

So that the Trojan will start when you start or restart Windows, the Trojan creates the following values:

• KazaaLoader    %windir%win32loader.exe
  
  in the registry key
  
  HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
  
• KazaaLoader    %windir%Win32loader.exe
  
  in the registry key
  
  HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices

In the registry key

HKEY_LOCAL_MACHINESoftwareCLASSESexefileshellopencommand

the Trojan changes the (Default) value to:

wmmiexe.exe "%1" %*

This causes the Trojan to run when you run an .exe file.

If the operating system is Windows 95/98/Me, the Trojan modifies the System.ini file and appends itself to the shell=Explorer.exe line in the [boot] section. Also, it modifies the Win.ini file and appends itself to the Run= line in the [windows] section of that file.

The Trojan attempts to disable some antivirus and firewall programs by ending their processes.

In addition, Backdoor.OptixPro.11 attempts to obtain an access to the password cache on the local computer. The cached passwords include modem and dial-up passwords, URL passwords, share passwords, and others. It enumerates successfully established RAS connection details to authenticate its access to the remote access server.

The Trojan installs hook procedures into a hook chain to monitor the system for any keyboard and mouse messages. The keyboard and mouse hook procedures process the messages and pass the hook information to the next hook procedure in the current hook chain. This permits Backdoor.OptixPro.11 to intercept keystrokes.

The Trojan notifies the client side using email. After Backdoor.OptixPro.11 is installed, it waits for commands from the remote client. The commands allow the hacker to perform any of the following actions:

• Deliver system and network information to the hacker, including login names and cached network passwords
• Steal login details of AOL Instant Messenger
• Print text, play media files, open or close the CD-ROM drive, and so on
• Manage the installation of the backdoor Trojan
• Download and execute files
• Use a known vulnerability in Windows 95/98/Me to cause the system to crash.

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

NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Do one of the following:
   • Windows 95/98/Me: Restart the computer in Safe mode.
   • Windows NT/2000/XP: Stop the Trojan process.
3. Run a full system scan, and delete all files that are detected as Backdoor.OptixPro.11.
4. Reverse the changes that the Trojan made to the registry.
5. (Windows 95/98/Me only) Restore the shell= line in the System.ini file, and restore the run= line in the Win.ini file.
   

For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:

• Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
• Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
  
  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.

To restart the computer in Safe mode or end the Trojan process:
Windows 95/98/Me
Restart the computer in Safe mode. All Windows 32-bit operating systems, except for 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.

Windows NT/2000/XP
To end the Trojan process:

1. Press Ctrl+Alt+Delete one time.
2. Click Task Manager.
3. Click the Processes tab.
4. Double-click the Image Name column header to sort the processes alphabetically.
5. Scroll through the list, and look for Win32loader.exe.
6. If you find the file, click it, and then click End Process.
7. Exit the Task Manager.

To scan for and delete the infected files:

1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
   • Norton AntiVirus consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • Symantec enterprise antivirus products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
2. Run a full system scan.
3. If any files are detected as infected with Backdoor.OptixPro.11, click Delete.

To reverse the changes that the Trojan made to the registry:
Because the Trojan modified the registry so that you cannot run .exe files, you must first make a copy of the Registry Editor as a file with the .com extension and then run that file.

To make a copy of the Registry Editor:

1. Do one of the following, depending on which version of Windows you are running:
   • Windows 95/98: Click Start, point to Programs, and click MS-DOS Prompt. A DOS window opens at the C:Windows prompt. Proceed to step 2 of this section.
   • Windows Me: Click Start, point to Programs, point to Accessories, and then click MS-DOS Prompt. A DOS window opens at the C:Windows prompt. Proceed to step 2 of this section.
   • Windows NT/2000:
     1. Click Start, and click Run.
     2. Type the following, and then press Enter:
        
        command
        
        A DOS window opens.
        
     3. Type the following, and then press Enter:
        
        cd winnt
        
     4. Go on to step 2 of this section.
        
   • Windows XP:
     1. Click Start, and click Run.
     2. Type the following, and then press Enter:
        
        command
        
        A DOS window opens.
        
     3. Type the following, and then press Enter after typing each one:
        
        cd
        cd windows
        
     4. Proceed to step 2 of this section.
        
2. Type the following, and then press Enter:
   
   copy regedit.exe regedit.com
   
3. Type the following, and then press Enter:
   
   start regedit.com
   
   The Registry Editor opens in front of the DOS window. After you finish editing the registry, exit the Registry Editor, and then exit the DOS window.
   

To edit 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 only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

1. Navigate to and select the following key:
   
   HKEY_LOCAL_MACHINESoftwareClassesexefileshellopencommand
   
   CAUTION: The HKEY_LOCAL_MACHINESoftwareClasses key contains many subkey entries that refer to other file extensions. One of these file extensions is .exe. Changing this extension can prevent any files ending with an .exe extension from running. Make sure that you browse all the way along this path until you reach the command subkey.
   
   Modify the HKEY_LOCAL_MACHINESoftwareClassesexefileshellopencommand subkey that is shown in the following figure:
   
   <<=== NOTE: Modify this key.
   
2. In the right pane, double-click the (Default) value.
3. Delete the current value data, and then type: "%1" %* (That is, type the following characters: quote-percent-one-quote-space-percent-asterisk.)
   
   NOTES:
   • On Windows 95/98/Me/NT, the Registry Editor automatically encloses the value within quotation marks. When you click OK, the (Default) value should look exactly like this:
     
     ""%1" %*"  
     
   • On Windows 2000/XP, the additional quotation marks will not appear. When you click OK, the (Default) value should look exactly like this:
     
     "%1" %*
     
   • Make sure that you completely delete all value data in the command key before you type the correct data. If you leave a space at the beginning of the entry, any attempt to run program files will result in the error message, "Windows cannot find .exe." If this happens to you, start over at the beginning of this document, and make sure that you completely remove the current value data.
     
4. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
5. In the right pane, delete the value
   
   KazaaLoader    %windows%win32loader.exe
   
6. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices
   
7. In the right pane, delete the following value (this may only appear on Windows 95/98/Me):
   
   KazaaLoader    %windows%win32loader.exe
   
8. Exit the Registry Editor.

To edit the System.ini and Win.ini files (Windows 95/98/Me only):

1. Click Start, and click Run.
2. Type the following and then click OK:
   
   edit c:windowssystem.ini
   
   The MS-DOS Editor opens.
   
   NOTE: If Windows is installed in a different location, make the appropriate path substitution.
   
3. In the [boot] section of the file, look for an entry similar to the following:
   
   shell=Explorer.exe <the Trojan file name>
   
4. Delete all text (on the shell=Explorer.exe line only) that is to the right of Explorer.exe. When you have finished, the line should read:
   
   shell=Explorer.exe
   
5. Click File, click Exit, and then click Yes when you are prompted to save the changes.
6. Click Start, and click Run.
7. 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.
   
8. In the [windows] section of the file, look for an entry similar to the following:
   
   run=<the Trojan file name>
   
9. Delete all text (on the run= line only) that is to the right of run=. When you have finished, the line should read:
   
   run=
   
10. Click File, click Exit, and then click Yes when you are prompted to save the changes.