Java Hacker Uncovers Two Flaws In Latest Update

Expert Java bug hunter says Oracle's latest Java 7 update, released last week, has two sandbox-bypass bugs.

Mathew J. Schwartz, Contributor

January 22, 2013

4 Min Read

The Java vulnerability news isn't getting better.

Less than one week after Oracle released Java 7 update 11 to patch or mitigate two zero-day vulnerabilities in Java that were being actively exploited by attackers, veteran Java bug hunter Adam Gowdiak of Security Explorations in Poland discovered two new vulnerabilities in Java standard edition.

"We have successfully confirmed that a complete Java security sandbox bypass can be still gained under the recent version of Java 7 Update 11 (JRE version 1.7.0_11-b21)," wrote Gowdiak in a post to the Full Disclosure mailing list. As a result, any attacker who used the vulnerabilities would be able to craft malware that tapped the Java runtime environment, thus fully compromising a vulnerable system.

Interestingly, the two newly discovered bugs have nothing to do with Oracle's partial patch of the "MBeanInstantiator" flaw. This was mitigated by Oracle via changing the default Java security setting from medium to high, which requires that an unsigned Java Web apps be authorized by a user before being allowed to run. "MBeanInstantiator bug (or rather a lack of a fix for it) turned out to be quite inspirational for us," said Gowdiak. "However, instead of relying on this particular bug, we have decided to dig our own issues. As a result, two new security vulnerabilities (51 and 52) were spotted in a recent version of Java SE 7 code and they were reported to Oracle today (along with a working Proof of Concept code)."

[ Questions about the latest Java bugs? Here are some answers. Java Security Warnings: Cut Through The Confusion. ]

Gowdiak has numbered the security vulnerabilities 51 and 52, because that's the number of Java 7 bugs Security Explorations has reported to Oracle since April 2, 2012. In terms of the latest two vulnerabilities reported to Oracle, Gowdiak said, "The company informs us that it will investigate based on the data provided and get back to us soon."

How bad are the vulnerabilities? "[Gowdiak] implies that although it locked the office door in update 7u11, Oracle left the entrance to the building open, which he considered as good as an invitation to find another way in," wrote Paul Ducklin, head of technology for Sophos in the Asia Pacific region, in a blog post. But per its disclosure policy, Security Explorations has yet to release full details of the new vulnerabilities, pending a fix from Oracle.

News of two new vulnerabilities being discovered comes on the heels of news that another Java vulnerability, unpatched by Oracle, was being offered for sale on an exclusive cybercrime forum.

The recently discovered Java vulnerabilities have led to widespread confusion over exactly which types of Java are at risk, worries about whether Java itself is safe, and questions over how Java-dependent enterprises should best deal with the vulnerability challenge. (Hint: Start by removing the Java plug-in from browsers, whenever possible.)

Oracle has also come under fire for failing to provide enterprises with a reliable method for updating the Java runtime environment across a large number of managed machines. As noted by one reader, "there are loosely published methods to do it via Group Policy or Configuration Manager, but these often fail, and are NOT supported by Oracle."

Despite all of the bad press Oracle has been lately receiving on the bug front, Gowdiak -- who's criticized the speed with which Oracle has issued Java patches -- says that Java is actually quite secure by design. "Contrary to the common belief, it is not so easy to break Java," he said in a Java security FAQ. "For a reliable, non-memory-corruption-based exploit codes, usually more than one issue needs to be combined together to achieve a full JVM sandbox compromise. This alone is both challenging and demanding as it usually requires a deep knowledge of a Java VM implementation and the tricks that can be used to break its security."

On the upside, Oracle also appears to have been taking a more aggressive approach to patching Java of late, according to Sophos's Ducklin. "Oracle does seem to be learning something about the sociology of patching widely distributed, consumer-targeted software like Java: patch early, patch often, don't be in denial, and think of extra mitigations beyond what is strictly necessary."

Those improvements, Ducklin continued, include the recent Java 7 update 11 patch arriving more quickly than anticipated, a control panel that lets people disable Java in their browser, as well as the stricter default security settings for code signing.

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About the Author(s)

Mathew J. Schwartz


Mathew Schwartz served as the InformationWeek information security reporter from 2010 until mid-2014.

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