SymbOS.Sendtool.A

SUMMARY

SymbOS.Sendtool.A is a Trojan horse that runs on the Symbian operating system, which is the operating system used for Nokia series 60 mobile phones. The Trojan horse drops a hacktool that can be used to send malicious programs, such as variants of the SymbOS.PBStealer family of Trojans, to other mobile devices via Bluetooth.

The Trojan horse arrives on the compromised device as Fspreader.SIS. If the user opens this .sis file, the device Installer displays a dialog box to warn the user that the application may be coming from an untrusted source and may cause potential problems.

Protection

• Virus Definitions (LiveUpdate™ Daily) January 19, 2006
• Virus Definitions (LiveUpdate™ Weekly) January 25, 2006
• Virus Definitions (Intelligent Updater) January 19, 2006
• Virus Definitions (LiveUpdate™ Plus) January 19, 2006

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: Attempts to sent the file to the first Bluetooth-enabled device it finds.
• Degrades Performance: Scanning for Bluetooth devices may impact the overall performance of the device.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When SymbOS.Sendtool.A is executed, it performs the following actions:

1. Displays the following message:
   
   Install
   FSpreader
   
   
2. Installs itself as the following files:
   
   
   • C:systemappsFSpreaderFSpreader.rsc
   • C:systemappsFSpreaderFSpreader.app
   • C:systemappsFSpreaderPATH.TXT
     
     
3. Scans for Bluetooth-enabled devices. It repeatedly attempts to sent the file listed in C:systemappsFSpreaderPATH.TXT to the first Bluetooth-enabled device it finds.
   
   
4. The following file is also created by the device Installer, not the threat:
   
   systeminstallFspreader.SIS
   

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. Navigate to and delete the following malicious files:
   
   
   • C:systemappsFSpreaderFSpreader.rsc
   • C:systemappsFSpreaderFSpreader.app
   • C:systemappsFSpreaderPATH.TXT
   • systeminstallFspreader.SIS
     
     
4. Exit the file manager.