A vulnerability in Java Web Start may allow an untrusted application to grant itself permissions to overwrite any file that is writable by the user running the application. This would include the user's .java.policy file which would allow the application to invoke applets or Java Web Start applications that can execute arbitrary code with the permissions of the user running the untrusted application.

Sun acknowledges, with thanks, John Heasman of NGSSoftware Limited, for bringing this issue to our attention.

This issue can occur in the following releases:

Windows Platform

• Java Web Start in JDK and JRE 5.0 Update 11 and earlier
• Java Web Start in SDK and JRE 1.4.2_13 and earlier

Notes:

1. Java Web Start in JDK and JRE 6 are not affected by this issue.
2. The Solaris Operating System is not affected by this issue.
3. The Linux Operating System is not affected by this issue.

To determine the version of Java on a system, the following command can be run:

    % java -version
    java version "1.5.0_02-b09"

There are no reliable symptoms that would indicate the described issue has been exploited.

To work around the described issue, disable Java Web Start applications from being launched from a web browser as follows:

Internet Explorer:

1. Right click on the "Start" button and select "Explore"
2. In the "Start Menu" window, select "Tools" => "Folder Options"
3. From the "Folder Options" window, select the "File Types" tab
4. From the "Registered File Types" window, scroll down and locate the "JNLP - JNLP File"
5. Select the "JNLP - JNLP File" and click the "Delete" button

Mozilla:

1. Select "Preferences" under the browser's "Edit" menu
2. In the "Preferences" window, select "Helper Applications" located under the "Navigator" category
3. Under "Files types", scroll down and locate "application/x-java-jnlp-file"
4. Select "application/x-java-jnlp-file" and click the "Remove" button

Notes:

1. On Windows, applications may also be launched from the desktop icon or from the "Start" menu if a shortcut was previously created for an application. Unknown applications should not be launched through the desktop icon or the Start Menu. Shortcuts can be removed by using the Java Web Start Application Manager through the "Application/Remove Shortcut" menu item. For more information, see:

http://java.sun.com/j2se/1.5.0/docs/guide/javaws/developersguide/overview.html#jws

2. It is also possible to launch applications through the command line in Windows. Unknown applications should not be launched through the command line. Sites may consider renaming the Java Web Start launcher ("javaws.exe" for Windows) to prevent Java Web Start from launching.

The launcher can be found at:

Windows:

C:\Program Files\java\j2re1.5.0\javaws\javaws.exe

This issue is addressed in the following releases:

Windows Platform

• Java Web Start in JDK and JRE 5.0 Update 12 or later
• Java Web Start in SDK and JRE 1.4.2_14 or later

J2SE 5.0 is available for download at the following link:

http://java.sun.com/j2se/1.5.0/download.jsp

J2SE 1.4.2 is available for download at the following link:

http://java.sun.com/j2se/1.4.2/download.html

Note: When installing a new version of the product, it is recommended that the old affected versions be removed from your system. For more information, please see:

http://java.com/en/download/help/uninstall_java.xml

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