Trojan.Norio

1. Adds at least one of the following values:
   
   "Windows Update"="<file name>"
   "service"="<file name> delete"
   "service_ls"="<file name> delete"
   "Network Service"="<file name> -sr -0"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
   
   
2. Creates the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\WinUpdate
   
   which is used to store a unique identification number.
   
   
3. Adds entries to one of the files, %Windir%\Hosts or %Windir%\System32\drivers\etc\Hosts.
   These entries may redirect the following URLs to point to the local computer, which may result in error messages when you try to access them:
   
   www.coolwebsearch.org
   coolwebsearch.org
   www.coolwebsearch.info
   coolwebsearch.info
   www.searchcomplete.com
   searchcomplete.com
   www.coolsearcher.net
   coolsearcher.net
   www.adulthyperlinks.com
   adulthyperlinks.com
   www.allhyperlinks.com
   allhyperlinks.com
   www.white-pages.ws
   white-pages.ws
   www.clearsearch.net
   clearsearch.net
   www.youfindall.net
   youfindall.net
   www.coolwwwsearch.com
   coolwwwsearch.com
   www.unipages.cc
   unipages.cc
   www.sexy18.cc
   sexy18.cc
   www.trafficswitcher.com
   trafficswitcher.com
   www.trafficback.com
   trafficback.com
   www.selfbookmark.com
   selfbookmark.com
   
   
4. Modifies the value for:
   
   "SearchURL"
   
   in the registry key:
   
   HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
   
   
5. Modifies the values for:
   
   "Search Page"
   "Search Bar"
   
   in the registry key:
   
   HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
   
   
6. Modifies the values for:
   
   "Default_Search_URL"
   "Search Page"
   
   in the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Main
   
   
7. Modifies the values for:
   
   "SearchAssistant"
   
   in the registry key:
   
   HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Search
   
   
8. Modifies the values for:
   
   "SearchAssistant"
   "CustomizeSearch"
   
   in the registry key:
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Search
   
   
9. Monitors open Web browser windows. If the title of an open Web page contains strings that the Trojan determines are characteristic of a porn site, it will open another porn site in a new browser window.
   
   
10. Periodically contacts a Web server for instructions. The response contains the URL for a file, which the Trojan will download and execute. This functionality may be used to update the Trojan or run any other code on a compromised system.
    
    
11. The Trojan may delete itself when the computer restarts.

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.