Printer Friendly Page

Discovered: February 28, 2006
Updated: February 13, 2007 12:51:36 PM
Also Known As: Trojan-SMS.J2ME.RedBrowser.a [, J2ME/RedBrowser.A [McAfee], RedBrowser.A [Panda Software], Redbrowser.A [F-Secure], SYMBOS_REDBROW.A [Trend]
Type: Trojan Horse
Systems Affected: Java

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:

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

Antivirus Protection Dates

  • Initial Rapid Release version February 28, 2006
  • Latest Rapid Release version November 04, 2019 revision 019
  • Initial Daily Certified version February 28, 2006
  • Latest Daily Certified version November 04, 2019 revision 065
  • Initial Weekly Certified release date March 01, 2006

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Technical Description

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

  1. Copies itself as the following Java archive (.jar) file:


    This archive contains the following files:

    • - 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.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.


  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:


  4. Delete the following files:

    • FS.class
    • FW.class
    • M.class
    • SM.class
    • icon.png
    • logo101.png
    • logo128.pnh

  5. Exit the file manager.

Writeup By: Yana Liu