iDEFENSE Security Advisory 11.22.04: Sun Java Plugin Arbitrary Package Access Vulnerability

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Date: 11/22/04

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    Sun Java Plugin Arbitrary Package Access Vulnerability

    iDEFENSE Security Advisory 11.22.04
    November 22, 2004


    Java Plug-in technology, included as part of the Java 2 Runtime
    Environment, Standard Edition (JRE), establishes a connection between
    popular browsers and the Java platform. This connection enables applets
    on Web sites to be run within a browser on the desktop. More information
    about Java Plug-in technology is available from


    Remote exploitation of a design vulnerability in Sun Microsystems Inc.'s
    Java Plug-in technology allows attackers to bypass the Java sandbox and
    all security restrictions imposed within Java Applets.

    A number of private Java packages exist within the Java Virtual Machine
    (VM) and are used internally by the VM. Security restrictions prevent
    Applets from accessing these packages. Any attempt to access these
    packages, results in a thrown exception of 'AccessControlException',
    unless the Applet is signed and the user has chosen to trust the issuer.

    The problem specifically exists within the access controls of the Java
    to Javascript data exchange in web browsers using Sun's Java Plug-in
    technology. The vulnerability allows Javascript code to load an unsafe
    class which should not normally be possible from a Java Applet.


    Successful exploitation allows remote attackers to execute hostile
    Applets that can access, download, upload or execute arbitrary files as
    well as access the network. A target user must be running a browser on
    top of a vulnerable Java Virtual Machine to be affected. It is possible
    for an attacker to create a cross-platform, cross-browser exploit for
    this vulnerability. Once compromised, an attacker can execute arbitrary
    code under the privileges of the user who instantiated the vulnerable


    iDEFENSE has confirmed the existence of this vulnerability in Java 2
    Platform, Standard Edition (J2SE) 1.4.2_01 and 1.4.2_04 from Sun
    Microsystems. It is suspected that earlier versions are vulnerable as
    well. Various browsers such as Internet Explorer, Mozilla and Firefox on
    both Windows and Unix platforms can be exploited if they are running a
    vulnerable Java Virtual Machine.


    Disabling Java or JavaScript will prevent exploitation as the
    vulnerability relies on the data transfer between the two components.
    Other Java Virtual Machines, such as the Microsoft VM, are available and
    can be used as an alternative.


    This issue has been fixed in J2SE v 1.4.2_06 available at:


    The Common Vulnerabilities and Exposures (CVE) project has assigned the
    name CAN-2004-1029 to this issue. This is a candidate for inclusion in
    the CVE list (, which standardizes names for
    security problems.


    06/29/2004 Initial vendor notification
    06/30/2004 Initial vendor response
    08/16/2004 iDEFENSE clients notified
    11/22/2004 Public disclosure


    Jouko Pynnonen (jouko[at] is credited with this discovery.

    Get paid for vulnerability research


    Copyright (c) 2004 iDEFENSE, Inc.

    Permission is granted for the redistribution of this alert
    electronically. It may not be edited in any way without the express
    written consent of iDEFENSE. If you wish to reprint the whole or any
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    email for permission.

    Disclaimer: The information in the advisory is believed to be accurate
    at the time of publishing based on currently available information. Use
    of the information constitutes acceptance for use in an AS IS condition.
    There are no warranties with regard to this information. Neither the
    author nor the publisher accepts any liability for any direct, indirect,
    or consequential loss or damage arising from use of, or reliance on,
    this information.

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