SymbOS.Bootton.E is a Trojan horse that restarts the mobile device when executed. However, as it also drops corrupted components, the device is unable to restart. The Trojan runs on the Symbian OS, which is used as the operating system for Nokia Series 60 cellular telephones. The Trojan reportedly arrives as Restart.S60.SIS. When the user clicks on the .sis file, the phone installer displays a dialog box to warn the user that the application may be coming from an untrusted source and may cause potential problems.

Technical Details

When SymbOS.Bootton.E is executed, it performs the following actions:

1. Displays the following message:
   
   Restart
   
2. Drops the following files on the compromised device:
   
   [DRIVE LETTER]:\Restart.dll
   [DRIVE LETTER]:\LayoutInst.dll
   [DRIVE LETTER]:\System\Apps\Restart\Restart.APP
   [DRIVE LETTER]:\System\Apps\Restart\Restart.AIF
   
   Note:
   The files restart the mobile device when executed, but due to the presence of the corrupted components, the device is unable to restart.
   The [DRIVE LETTER] variable refers to the drive letter that is used to represent the device itself or the memory card. The actual value will depend on the choice the user makes during the installation process.
   
3. The following file is also created by the Installer, not the threat:
   
   \system\install\Restart.S60.SIS
   
4. Displays the following message during installation:
   
   This app can restart your phone by only clicking on the restart icon. It is suitable for S60 phones. Enjoy!!
   Created By:
   Symbian Corporation ©2006

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 Instructions

1. Install a file manager program on the device.
2. Enable the option to view the files in the system folder.
3. Navigate to and delete the following malicious files:
   
   [DRIVE LETTER]:\Restart.dll
   [DRIVE LETTER]:\LayoutInst.dll
   [DRIVE LETTER]:\System\Apps\Restart\Restart.APP
   [DRIVE LETTER]:\System\Apps\Restart\Restart.AIF
   
4. Exit the file manager.

http://www.symantec.com/avcenter/venc/data/symbos.bootton.e.html