Sun Java Plugin Arbitrary Package Access Vulnerability

iDEFENSE Security Advisory 11.22.04
www.idefense.com/application/poi/display?id=3D158&type=3Dvulnerabilities
November 22, 2004

I. BACKGROUND

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
http://java.sun.com/products/plugin/.

II. DESCRIPTION

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.

III. ANALYSIS

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
browser.

IV. DETECTION

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.

V. WORKAROUND

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.

VI. VENDOR RESPONSE

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

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

VII. CVE INFORMATION

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 (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

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

IX. CREDIT

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

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X. LEGAL NOTICES

Copyright (c) 2004 iDEFENSE, Inc.

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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.