W32.Scrapkut

The worm arrives as a comment, commonly called a scrap, in the Orkut user's scrapbook.

The worm uses a GreaseMonkey script to send a scrap to all contacts in the user's address book. The scrap contains a Youtube-like image that redirects the browser to the following URL:
[http://]instantflashx.zip.net/watch[REMOVED]

The above site prompts the user to download Macromedia Flash Player in order to play the video. However, the link is actually pointing to the following URL, which is a copy of the worm:
[http://]installgetflash.blogcindario.com/ficheros/flashx_play[REMOVED]

When downloaded and executed, it displays a message box in Portuguese stating that the plugin has been successfully installed.

The worm also downloads potentially malicious files from the following URLs:

• [http://]avdetectordok.ifastnet.com/vaiprim[REMOVED]
• [http://]pluginforweb22.ifastnet.com/auook[REMOVED]
• [http://]youprincipalpug.ifastnet.com/gamesys[REMOVED]

Note: It saves them as the following files:

• %Windir%\windosremote.exe
• %Windir%\logservicess.exe
• %Windir%\win32chekupdate.exe

Next, the worm executes a batch file that attempts to end antivirus-related processes.

It then executes the file %Windir%\win32chekupdate.exe which is Infostealer.Skrapcut.

The worm injects JavaScript code into the Internet Explorer process.

The worm spreads by sending scraps to all contacts when the user logs in to Orkut from the compromised computer.

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