SymbOS.Fontal.D

SUMMARY

SymbOS.Fontal.D is a Trojan horse that runs on the Symbian OS, which is used as the operating system for Nokia Series 60 cellular telephones. It drops a corrupted Font file, which will cause the compromised device to fail at next reboot. It also attempts to disable Kaspersky Anti-Virus for Symbian by overwriting the files associated with this application.

SymbOS.Fontal.D reportedly arrives as Nokia Anti-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

Distribution

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

TECHNICAL DETAILS

When SymbOS.Doomboot.Q is executed, it performs the following actions:

1. Copies itself as the following file:
   
   Nokia Anti-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 phone will display a message prompting the user to Install:
   
   
   
   
3. Drops the following files:
   
   
   • C:SystemappsKASKAS
   • C:SystemappsKASs.mid
   • C:SystemappsKASlnotify.mbm
   • C:SystemappsKASlnotify.rsc
   • C:SystemappsKASlnotify.app
   • C:SystemappsKASlimages.mbm
   • C:SystemappsKASKAS_caption.r01
   • C:SystemappsKASKaS.aif
   • C:SystemappsKASEngine.exe
   • C:SystemappsKAS.dat
   • C:SystemappsKASKAS.r01
   • C:SystemFontsKaspersky.gdr, SymbOS.Fontal.A
   • C:SystemhelpKasAntivirusHelp.hlp
   • C:Systemlibskasdll.dll
   • C:Systemecogskas_antivirus.mdl
     
     
4. Displays the following message after installation:
   
    
   
   
5. Creates the following file:
   
   C:systeminstallNokia Anti-Virus.sis
   
   Note: This file is actually created by the phone installer, not the threat.

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 file:
   
   Nokia Anti-Virus.SIS
   
   
4. Navigate to the following folder:
   
   C:System
   
   
5. Delete the following files:
   
   
   • appsKASKAS
   • appsKASs.mid
   • appsKASlnotify.mbm
   • appsKASlnotify.rsc
   • appsKASlnotify.app
   • appsKASlimages.mbm
   • appsKASKAS_caption.r01
   • appsKASKaS.aif
   • appsKASEngine.exe
   • appsKAS.dat
   • appsKASKAS.r01
   • FontsKaspersky.gdr, SymbOS.Fontal.A
   • helpKasAntivirusHelp.hlp
   • libskasdll.dll
   • ecogskas_antivirus.mdl
     
     
6. Exit the file manager.