Backdoor.Akak

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%\rb.exe.
   
   Note: %System% is a variable that refers to the System folder. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).
   
   
5. Creates the value:
   
   "RamBooster2"="%System%\rb.exe "
   
   in the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   
   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":

• 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.

Summary