What is the vulnerability?
The new Java vulnerability with no patch has become the talk of the town. The vulnerability in Oracle Java Runtime Environment (JRE) 1.7 allows an applet to call setSecurityManager in a way that allows setting of arbitrary permissions.
Note: This is a vulnerability in Java and not Javascript.
How does it work?
Java Runtime Environment (JRE) 1.7 allows users to run Java applications standalone programs/browsers. 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 Security Exception”. The vulnerability is caused when the JRE fails to properly restrict access to the setSecurityManager() function, which can allow an unprivileged Java applet to set its own privileges. This results in the Java sandbox being bypassed.
Exploit code: http://pastie.org/4594319
What does it affect?
- Most of the recent Java run-time environments i.e., JRE 1.7x are vulnerable. This vulnerability affects Java 7 (1.7) Update 0 to 6. Does NOT affect Java 6 and below.
- The publicly available exploits work on all versions of Internet Explorer, Firefox, and Opera. It also works on Chrome in Windows XP, Safari on OS X 10.7.4.
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What are the risks?
- This vulnerability is being actively exploited in the wild, and exploit code is 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 and thus install malware including remotely controllable trojans and rootkits.
How to safeguard?
The is no patch from Oracle yet. For now, completely disable Java until a fix is available.
Disabling the Java browser plugin may prevent a malicious webpage from exploiting this vulnerability.
- Apple Safari: How to disable the Java web plug-in in Safari
- Firefox: How to turn off Java applets
- Microsoft Internet Explorer: Refer to the Java documentation for more details. In the Windows Control panel, open the Java item. Select the “Java” tab and click the “View” button. Uncheck “enabled” for any JRE version listed. Or you can also check the following link.
- Chrome: See the “Disable specific plug-ins” section of the Chrome documentation for how to disable Java in Chrome.
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Use NoScript
Using the Mozilla Firefox NoScript extension to whitelist web sites that can run scripts and access installed plugins will mitigate this vulnerability. See the NoScript FAQ for more information.
Funny Tweet by: Info Security Jerk @infosecjerk
“If I hear another clueless IT person tell someone to disable JavaScript when they mean Java, I will prepare my blowtorch.”
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