Trojan.Redbrowser.A

SUMMARY

Trojan.Redbrowser.A is a Trojan horse that sends premium-rate SMS messages. It is a Java Midlet application that runs on mobile devices which have the Java 2 Micro Edition (J2ME) installed. It may be downloaded to the compromised device from the Internet or via Bluetooth. It may also be transferred to the device from a computer.

The Trojan arrives as the following program, which attempts to trick users into believing it is a legitimate application that allows users to visit WAP sites without using a WAP connection:
RedBrowser.

Note: Definitions dated prior to March 1, 2006 detect this threat as SymbOS.Redbrowser.A.

Protection

• Virus Definitions (LiveUpdate™ Daily) February 28, 2006
• Virus Definitions (LiveUpdate™ Weekly) March 1, 2006
• Virus Definitions (Intelligent Updater) February 28, 2006
• Virus Definitions (LiveUpdate™ Plus) February 28, 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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When Trojan.Redbrowser.A is executed, it performs the following actions:

1. Copies itself as the following Java archive (.jar) file:
   
   redbrowser.jar
   
   
   
   This archive contains the following files:
   
   
   • Manifest.mf - 321 bytes
   • FS.class - 2,719 bytes
   • FW.class - 2,664 bytes
   • M.class - 5,339 bytes
   • SM.class - 1,945 bytes
   • icon.png - An image file 3,165 bytes
   • logo101.png - An image file 16,829 bytes
   • logo128.pnh - An image file 27,375 bytes
     
     
2. Displays an image of a red moon while the application loads.
   
   
   
   
3. Displays a fake message in Russian to trick the user into allowing the Trojan to use Java SMS capabilities on the compromised device.
   
   
   
   
4. Randomly chooses a premium-rate number from the following predetermined list:
   
   
   • 08293538938
   • 08001738938
   • 08180238938
   • 08229238938
   • 08441238938
   • 08287038938
   • 08187938938
   • 08189038938
   • 08217838938
   • 08446838938
     
     
5. Sends an SMS message to randomly chosen premium-rate number.
   
   
6. Continually prompts the user to send successive SMS messages. If the user agrees to send the messages, the threat will continue to prompt to send more messages.

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:
   
   redbrowser.jar
   
   
4. Delete the following files:
   
   
   • Manifest.mf
   • FS.class
   • FW.class
   • M.class
   • SM.class
   • icon.png
   • logo101.png
   • logo128.pnh
     
     
5. Exit the file manager.