Zscaler Blog

You may be aware that a 0-day vulnerability in the latest version of Java is presently being exploited on the Web. This vulnerability affects all versions of Java 1.7 (aka Java 7). Oracle has not yet released a fix and if they stick to their quarterly patch cycle, one isn't likely to emerge until October.

Java has a long history of 0-day vulnerabilities being actively exploited. Exploits are usually drive-by attacks: users get infected by navigating to hijacked websites where an invisible Java applet drops a malicious executable on the user's machine. The very popular, Blackhole exploit kit includes numerous Java exploits.

In 2010, we reported a 300% increase of malicious JAR (Java archive) files. Recently, in March 2012, Java made the news due to the Flashback Trojan, a piece malware targeting an older Java version that shipped with Mac OS X. As can be seen, Java is constantly under attack.

Update: new Java version available

Oracle has released java 1.7.7 and 1.6.35 to fix the vulnerability. You can update your java version from Java.com.

We have updated our Java test page to take the new versions into account.

Are you vulnerable?

The latest iteration of Java is version 1.7 revision 6. This is now the default version on Windows. Mac OS X still uses Java 1.6 (latest version: 1.6.33). Java 1.6.33 is NOT vulnerable to the latest 0-day exploit. However, I would not suggest that anybody downgrade from Java 1.7 to Java 1.6 as it is not yet known if version 1.6 is vulnerable to other flaws fixed in 1.7.

One annoying fact with Java is that new versions are installed on top of each other. As such, you are likely to have multiple versions of Java installed on your system. Internet Explorer may not even be using the latest version of Java that you have installed.

We have created a new page to list all of the versions of Java installed on your computer. You can test your browser here.

Disable Java

To be on the safe side, you can disable Java in your browser to prevent malicious applets from running.

Firefox

Go to Tools - Add-ons - Plugins

Look for Java Deployment Toolkit and/or Java Platform SE. Disable them all.

Java disabled in Firefox

Chrome

Go to Wrench -  Settings and Show advanced settings... - Privacy and Content settings - Plug-ins - Disable individual plug-ins... - Java - disable. It is quite difficult to find!

Java enabled in Chrome

Internet Explorer

Go to Tools - Manage Add-ons. Disable Java(tm) Plug-in SSV Helper and Java(tm) Plug-in 2 SSV Helper.

Java disabled in Internet Explorer 9

Update: To completely disable Java in Internet Explorer, follow the steps at http://www.kb.cert.org/vuls/id/636312#disable_java_in_IE.


Test it

Now go to our Java test page (updated) to ensure that Java has indeed been disabled in your browser.

Click to Play

If you need Java occasionally, you can enable it on-demand with Click to Play. I described Click to Play, a way to manually enable plugins only on visible content, in a previous post. This feature is only available in Firefox, Chrome and Opera.

Firefox also offers several browser extensions to easily enable/disable java with one click. I personally like Quick Java.

Take this opportunity to check all the plugins running in your browser and disable the plugins that you do not really need. Don't give the bad guys an attack surface that's any larger than it needs to be!