Backdoor.Akak

SUMMARY

Backdoor.Akak is a backdoor server that also creates a SOCKS proxy on the compromised system. Reports indicate that Web sites exploiting the Microsoft Internet Explorer Drag And Drop File Installation Vulnerability may install it.

Protection

• Virus Definitions (LiveUpdate™ Weekly) September 8, 2004
• Virus Definitions (Intelligent Updater) September 3, 2004

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
• Releases Confidential Info: Opens an unauthorized backdoor to the compromised system.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Backdoor.Akak is a backdoor server program that may be installed when you visit a malicious Web site using Internet Explorer. These pages may contain code that exploits the Microsoft Internet Explorer Drag And Drop File Installation Vulnerability.

If Backdoor.Akak runs, it will download the file, Testexe.exe or Rb.exe, to the Windows Startup folder.

Following this, when you start Windows, it does the following:

1. Executes the downloaded file.
   
   
2. Creates the mutex "J&^srl!hsl^AHSgh" so that only one instance of the backdoor is present in memory.
   
   
3. Registers itself as a service so that it continues to run even if you log off.
   
   
4. Copies itself as %System%b.exe.
   
   Note: %System% is a variable that refers to the System folder. By default, this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
   
   
5. Creates the value:
   
   "RamBooster2"="%System%b.exe "
   
   in the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   so that the Trojan runs every time that Windows starts.
   
   
6. Issues the command "net stop SharedAccess" to disable the Windows Internet Connection Firewall (ICF), if it is running on the system. (Windows 2000/XP).
   
   
7. Contacts a master server located at 202.104.242.156 on TCP port 4321 and downloads information, which is stored in the file, %System%lhosts.txt.
   
   
8. If the backdoor cannot create the lhosts.txt file, it will instead store this information in the file, Kaka2.txt, which it creates in the current working folder.
   
   
9. Creates a SOCKS proxy on TCP port 5555. This allows the compromised computer to be used to proxy protocols such as HTTP.
   
   
10. Listens on TCP port 4321 for commands from the remote attacker. The attacker can do any of the following:
    • Obtain system information
    • Download and execute files on the compromised computer
    • Uninstall the back door
    • Update the address of the master server

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

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Run a full system scan and delete all the files detected as Backdoor.Akak.
4. Delete the value that was added to the registry.
5. Re-enable the SharedAccess service (Windows 2000/XP only).
   

For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

• "How to disable or enable Windows Me System Restore"
• "How to turn off or turn on Windows XP System Restore"

Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.


For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.

2. To update 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 daily. 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: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. To scan for and delete the infected files

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that 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.Akak, click Delete.
   
   
   Note: If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix this, run the scan in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode." Once you have restarted in Safe mode, run the scan again.
   
   (After the files are deleted, you can leave the computer in Safe mode and proceed with section 4. When that is done, restart the computer in Normal mode.)
   

4. To delete the value from the registry


Important: Symantec strongly recommends that you back up the registry before making 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.

1. Click Start > Run.
2. Type regedit
   
   Then click OK.
   
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the value:
   
   "RamBooster2" =" %System%b.exe"
   
   
5. Exit the Registry Editor.

5. To re-enable the SharedAccess service (Windows 2000/XP only)
The SharedAccess service is responsible for maintaining Internet Connection Sharing and the Windows Firewall/Internet Connection Firewall applications in Windows. (The presence and names of these applications vary depending on the operating system and service pack you are using.) To protect your computer and maintain network functionality, re-enable this service if you are using any of these programs.


Windows XP Service Pack 2
If you are running Windows XP with Service Pack 2 and are using the Windows Firewall, the operating system will alert you when the SharedAccess service is stopped, by displaying an alert balloon saying that your Firewall status is unknown. Perform the following steps to ensure that the Windows Firewall is re-enabled:

1. Click Start > Control Panel.
   
   
2. Double-click the Security Center.
   
   
3. Ensure that the Firewall security essential is marked ON.
   
   Note: If the Firewall security essential is marked on, your Windows Firewall is on and you do not need to continue with these steps.
   
   If the Firewall security essential is not marked on, click the "Recommendations" button.
   
   
4. Under "Recommendations," click Enable Now. A window appears telling you that the Windows Firewall was successfully turned on.
   
   
5. Click Close > OK.
   
   
6. Close the Security Center.

Windows 2000 or Windows XP Service Pack 1, or earlier
Complete the following steps to re-enable the SharedAccess service:

1. Click Start > Run.
2. Type services.msc
   
   Then click OK.
   
   
3. Do one of the following:
   
   • Windows 2000: Under the Name column, locate the "Internet Connection Sharing (ICS)" service and double-click it.
   • Windows XP: Under the Named column, locate the "Internet Connection Firewall (ICF) / Internet Connection Sharing (ICS)" service and double-click it.
     
     
4. Under "Startup Type:", select "Automatic" from the drop-down menu.
   
   
5. Under "Service Status:", click the Start button.
   
   
6. Once the service has completed starting, click OK.
   
   
7. Close the Services window.