US-CERT Alert TA12-240A - Oracle Java 7 Security Manager Bypass Vulnerability

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National Cyber Awareness System

US-CERT Alert TA12-240A
Oracle Java 7 Security Manager Bypass Vulnerability

Original release date: August 27, 2012
Last revised: –

Systems Affected

 Any system using Oracle Java 7 (1.7, 1.7.0) including:

 * Java Platform Standard Edition 7 (Java SE 7)
 * Java SE Development Kit (JDK 7)
 * Java SE Runtime Environment (JRE 7)

 Web browsers using the Java 7 Plug-in are at high risk.

Overview

A vulnerability in the way Java 7 restricts the permissions of Java
applets could allow an attacker to execute arbitrary commands on a
vulnerable system.

Description

A vulnerability in the Java Security Manager allows a Java applet
to grant itself permission to execute arbitrary operating system
commands. An attacker could use social engineering techniques to
entice a user to visit a link to a web site hosting a malicious
applet.

Any web browser using the Java 7 Plug-in is affected.

Reports indicate this vulnerability is being actively exploited,
and exploit code is publicly available.

Impact

By convincing a user to load a malicious Java applet, an attacker
could execute arbitrary operating system commands on a vulnerable
system with the privileges of the Java Plug-in process.

Solution

Disable the Java Plug-in

Disabling the Java web browser plug-in will prevent Java applets
from from running. Here are instructions for several common web
browsers:

• Apple Safari: How to disable the Java web plug-in in Safari

• Mozilla Firefox: How to turn off Java applets

• Google Chrome: See the "Disable specific plug-ins" section of the
  Chrome Plug-ins documentation.

• Microsoft Internet Explorer: Change the value of the
  UseJava2IExplorer registry key to 0. Depending on the versions of
  Windows and the Java plug-in, the key can be found in these
  locations:

  HKLM\Software\JavaSoft\Java Plug-in\{version}\UseJava2IExplorer

  HKLM\Software\Wow6432Node\JavaSoft\Java Plug-in\{version}\UseJava2IExplorer

• The Java Control Panel (javacpl.exe) does not reliably configure
  the Java plug-in for Internet Explorer. Instead of editing the
  registry, it is possible to run javacpl.exe as Administrator,
  navigate to the Advanced tab, Default Java for browsers, and use
  the space bar to de-select the Microsoft Internet Explorer option.

Use NoScript

NoScript is a browser extension for Mozilla Firefox browsers that
provides options to block Java applets.

References

• Vulnerability Note VU#636312
  <http://www.kb.cert.org/vuls/id/636312&gt;

• Zero-Day Season is Not Over Yet
  <http://blog.fireeye.com/research/2012/08/zero-day-season-is-not-over-yet.html&gt;

• Let's start the week with a new Java 0-day in Metasploit
  <https://community.rapid7.com/community/metasploit/blog/2012/08/27/lets-start-the-week-with-a-new-java-0day&gt;

• http://pastie.org/4594319
  <http://pastie.org/4594319&gt;

• The Security Manager
  <http://docs.oracle.com/javase/tutorial/essential/environment/security.html&gt;

• Java 7 0-Day vulnerability information and mitigation.
  <http://www.deependresearch.org/2012/08/java-7-0-day-vulnerability-information.html&gt;

• How to disable the Java web plug-in in Safari
  <https://support.apple.com/kb/HT5241&gt;

• How to turn off Java applets
  <https://support.mozilla.org/en-US/kb/How&#37;20to&#37;20turn&#37;20off&#37;20Java&#37;20applets&gt;

• NoScript
  <http://noscript.net/&gt;

Revision History

August 27, 2012: Initial release

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Feedback can be directed to US-CERT Technical Staff. Please send
email to <[email protected]> with "TA12-240A Feedback VU#636312" in
the subject.

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