Trojan.Adwareloader

1. Creates the mutex SouthPark, so that only one instance of the Trojan will run on the compromised computer.
   
   
2. Creates the following copies of itself:
   
   
   • %System%\[Trojan file name]
   • %System%\msoffice.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).
     
     
3. Adds the value:
   
   "WebRun" = "%System%\[Trojan file name]"
   
   to the registry subkey:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   
   so that it is executed every time Windows starts.
   
   
4. Adds the value:
   
   "run" = "%System%\msoffice.exe"
   
   to the registry subkey:
   
   HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
   
   so that it is executed every time Windows starts.
   
   
5. Adds the following line to the [Windows] section of the Win.ini file, on computers running Windows 95/98:
   
   run = %System%\msoffice.exe
   
   
6. Downloads several adware and spyware files from the private-admin.biz domain.
   
   
7. Downloads the file commands.ini from the private-admin.biz domain. This is an encrypted file that contains information on registry keys to be set.
   
   
8. Adds the value:
   
   "Cartman" = "[DWORD Value]"
   
   to the registry subkeys:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Main
   HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
   
   where [DWORD Value] is taken from the commands.ini file, and serves as a version number.
   
   
9. Modifies the following registry entry based on the contents of the commands.ini file:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main\Start Page
   
   This results in the Internet Explorer start pages being redirected.
   
   
10. Adds the following values:
    
    "FirewallDisableNotify" = "1"
    "UpdatesDisableNotify" = "1"
    "AntiVirusDisableNotify" = "1"
    
    to the registry subkeys:
    
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Security Center
    
    to disable several security features in Windows.
    
    
11. Adds the following values:
    
    "NoAutoUpdate" = "1"
    "AUOptions" = "1"
    
    to the registry subkeys:
    
    HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
    HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
    
    to disable several security features in Windows.
    
    
12. Adds the following value:
    
    "EnableFirewall" = "1"
    
    to the registry subkeys:
    
    HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall\StandardProfile
    HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall\DomainProfile
    HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\WindowsFirewall\StandardProfile
    HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\WindowsFirewall\DomainProfile
    
    to disable several security features in Windows.

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.