Symbos.Fontal.E

SUMMARY

SymbOS.Fontal.E is a Trojan horse that runs on the Symbian OS, which is used as the operating system for Nokia Series 60 cellular telephones. It installs a corrupt font file on the compromised device.

SymbOS.Fontal.E reportedly arrives as T-VIRUS.sis.

Protection

• Virus Definitions (LiveUpdate™ Weekly) December 7, 2005
• Virus Definitions (Intelligent Updater) December 3, 2005

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Low
• Payload: Installs a corrupt font file on the compromised device.
• Causes System Instability: Installation of corrupt font file may result in the device not starting correctly when restarted.

Distribution

• Distribution Level: Low
• Target of Infection: Symbian OS systems

TECHNICAL DETAILS

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

1. Copies itself as the following file:
   
   T-VIRUS.sis
   
   Note: If a user opens this file, the device Installer will display a dialog to warn the user that the application may be coming from an untrusted source and may cause potential problems.
   
   
2. If the user clicks yes, the device displays the following message prompting the user to Install:
   
   T-VIRUS
   
   
   
   
3. Displays the following message after installation:
   
   You infected by T-Virus Someone Has Infected you With The T-VIRUS transmitted by SMS or MMS you want Disinfect your phone please press OK and Restart your phone after installation complete to Disinfect
   
   
   
   
4. Installs the following file, which is a corrupt font file, on the compromised device:
   
   C:systemFontsT-VIRUS.gdr
   
   As a result of the installation of this file, the device will not start correctly if it is restarted. This file is detected as SymbOS.Fontal.A.

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

1. Install a file manager program on the device.
   
   
2. Enable the option to view the files in the system folder.
   
   
3. Delete the following malicious files:
   
   
   • T-VIRUS.sis
   • C:systemFontsT-VIRUS.gdr
     
     
4. Exit the file manager.