Major vulnerability found in Java

The Department of Homeland Security's United States Computer Emergency Readiness Team (US-CERT) has issued an alert that an unspecified vulnerability in Java can allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

The vulnerability affects Java 7 Update 10 and earlier versions. US-CERT reports it is currently unaware of a practical solution to this problem. It recommends working around the flaw by disabling Java in web browsers.

Here are the details:

The Oracle Java Runtime Environment (JRE) 1.7 enables users to run Java applications in a browser or as standalone programs. Oracle has made the JRE available for multiple operating systems.

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 unspecified vulnerabilities involving Java Management Extensions (JMX) MBean components and objects, an untrusted Java applet can escalate its privileges by calling the the setSecurityManager function to allow full privileges, without requiring code signing. 

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.

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.

Starting with Java 7 Update 10, it is possible to disable Java content in web browsers through the Java control panel applet. Please see the Java documentation for more details.
Note: Due to what appears to potentially be a bug in the Java installer, the Java Control Panel applet may be missing on some Windows systems. In such cases, the Java Control Panel applet may be launched by finding and executing javacpl.exe manually. This file is likely to be found in C:\Program Files\Java\jre7\bin or C:\Program Files (x86)\Java\jre7\bin.