Backdoor.OptixPro.10.b

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Discovered: December 17, 2002
Updated: February 13, 2007 11:51:30 AM
Also Known As: Backdoor.Optix.Pro.12 [KAV], BackDoor-ACH[McAfee]
Type: Trojan Horse
Systems Affected: Windows



Backdoor.OptixPro.10.b is variant of Backdoor.OptixPro.10 . This backdoor Trojan gives an attacker unauthorized access to an infected computer. By default it opens TCP port 8888 on the infected computer. This threat is written in the Borland Delphi programming language and is compressed with PECompact.

Antivirus Protection Dates

  • Initial Rapid Release version December 18, 2002
  • Latest Rapid Release version March 03, 2008 revision 035
  • Initial Daily Certified version December 18, 2002
  • Latest Daily Certified version March 03, 2008 revision 037
  • Initial Weekly Certified release date December 18, 2002

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.


Technical Description


When Backdoor.OptixPro.10.b runs, it does the following:

It copies itself as C:\%system%\Mep1e5.tmp.exe

NOTE:
%system% is a variable. The Trojan locates the System folder and copies itself to that location. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

The Trojan creates the value

InternalSystray    C:\%system%\mep1e5.tmp.exe

in the registry keys

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices

so that the Trojan starts each time that you start Windows.

It drops the file %windir%\Wmmiexe.exe. This file is detected by Symantec antivirus products as Trojan Horse.

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.

In the registry key

HKEY_LOCAL_MACHINE\Software\CLASSES\exefile\shell\open\command

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 System.ini and appends itself to the shell=Explorer.exe line in the [boot] section as the following:

[boot]
Shell=Explorer.exe C:\%system%\mep1e5.tmp.exe

If the operating system is Windows 95/98/Me, it appends itself to the Run= line in the [windows] section of Win.ini file:

[windows]
Run=C:\%system%\mep1e5.tmp.exe

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

In addition, Backdoor.OptixPro.10.b attempts to obtain 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 inventories 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.10.b to intercept keystrokes.

The Trojan notifies the client side through email. After Backdoor.OptixPro.10.b 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":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.


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.10.b.
  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 once.
    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.
  2. Run a full system scan.
  3. If any files are detected as infected with Backdoor.OptixPro.10.b, 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_MACHINE\Software\Classes\exefile\shell\open\command

    CAUTION: The HKEY_LOCAL_MACHINE\Software\Classes 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_MACHINE\Software\Classes\exefile\shell\open\command 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_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  5. In the right pane, delete the value

    InternalSystray    C:\%system%\mep1e5.tmp.exe
  6. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices
  7. In the right pane, delete the following value (this may only appear in Windows 95/98/Me):

    InternalSystray    C:\%system%\mep1e5.tmp.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:\windows\system.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:\windows\win.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 that is 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.


Writeup By: Yana Liu