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Vulnerability Note VU#625617

Java 7 fails to restrict access to privileged code

Original Release date: 10 Jan 2013 | Last revised: 14 Jan 2013

Overview

Java 7 Update 10 and earlier versions of Java 7 contain a vulnerability that can allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

Description

The Oracle Java Runtime Environment (JRE) 1.7 allows users to run Java applications in a browser or as standalone programs. Oracle has made the JRE available for multiple operating systems. OpenJDK is an open-source implementation of the Java platform, and the IcedTea project aims to make it easier to deploy OpenJDK, including a web browser plugin.

The Java JRE plug-in provides its own Security Manager. Typically, a web applet runs with a security manager provided by the browser or Java Web Start plugin. Oracle's document states, "If there is a security manager already installed, this method first calls the security manager's checkPermission method with a RuntimePermission("setSecurityManager") permission to ensure it's safe to replace the existing security manager. This may result in throwing a SecurityException".

By leveraging the a vulnerability in the Java Management Extensions (JMX) MBean components, unprivileged Java code can access restricted classes. By using that vulnerability in conjunction with a second vulnerability involving recursive use of the Reflection API via the invokeWithArguments method of the MethodHandle class, an untrusted Java applet can escalate its privileges by calling the the setSecurityManager() function to allow full privileges, without requiring code signing. Oracle Java 7 update 10 and earlier Java 7 versions are affected. OpenJDK 7, and subsequently IcedTea, are also affected. The invokeWithArguments method was introduced with Java 7, so therefore Java 6 is not affected.

This vulnerability is being attacked in the wild, and is reported to be incorporated into exploit kits. Exploit code for this vulnerability is also publicly available. We have confirmed that Windows, OS X, and Linux platforms are affected. Other platforms that use Oracle Java 7 may also be affected.

Impact

By convincing a user to visit a specially crafted HTML document, a remote attacker may be able to execute arbitrary code on a vulnerable system. Note that applications that use the Internet Explorer web content rendering components, such as Microsoft Office or Windows Desktop Search, may also be used as an attack vector for this vulnerability.