Java Emergency Patch Slaps McRAT Infections

Oracle released emergency updates Monday for both Java 6 and Java 7, patching two critical bugs.

One of the vulnerabilities, CVE-2013-1493, has been actively used by attackers to infect PCs with malware known as McRAT. The remote access Trojan (RAT) is designed to download further malware onto an infected PC. The other fix included in Oracle's Java patch, for "another closely related bug" (CVE-2013-0809), hasn't been seen in active attacks.

Oracle's related security alert said that because of the severity of the bugs -- which can be "remotely exploitable without authentication, i.e., they may be exploited over a network without the need for a username and password" -- all Java 6 and Java 7 users should immediately upgrade to the latest versions.

[ Should you trust Java? Read 10 Facts: Secure Java For Business Use. ]

"Both vulnerabilities affect the 2D component of Java SE," said Oracle software security assurance director Eric Maurice in a blog post, referring to a runtime graphics and rendering sub-component of Java. "These vulnerabilities are not applicable to Java running on servers, standalone Java desktop applications or embedded Java applications. They also do not affect Oracle server-based software," he said.

The latest versions of Java are now Java 7 update 17 and Java 6 update 43. Their release Monday marked the third time this year that Oracle has released patched Java, following an emergency update in January to fix a zero-day bug being exploited by attackers, as well as a regularly scheduled, quarterly release in February that fixed 50 bugs.

"As stated in previous blogs, Oracle is committed to accelerating the release of security fixes for Java SE, particularly to help address the security-worthiness of Java running in browsers," said Maurice. "The quick release of this Security Alert, the higher number of Java SE fixes included in recent Critical Patch Updates, and the announcement of an additional security release date for Java SE (the April 16th Critical Patch Update for Java SE) are examples of this commitment."

But the recent spate of Java bug reports have led to confusion over what types of Java are vulnerable to being attacked. In general, security experts have recommended that computer users disable the Java browser plug-in whenever possible, or else maintain a separate browser with the Java plug-in installed, and use that browser only with known, trusted websites.

The frequency with which newly discovered Java bugs have been used by attackers to exploit PCs -- often via automated crimeware toolkits -- has led to the creation of the Java zero-day exploit tracker. The site counts the number of days that have elapsed since a new Java zero-day attack has been seen.

Despite the release of Oracle's latest Java updates, don't expect Java bug fixes to stop coming anytime soon, as prolific Java bug hunter Adam Gowdiak, who heads Poland-based research firm Security Explorations, has spotted five new Java 7 bugs.

"Five new security issues were discovered in Java SE 7 (numbered 56 to 60), which when combined together can be successfully used to gain a complete Java security sandbox bypass in the environment of Java SE 7 update 15," Gowdiak said in a Monday message to the Bugtraq mailing list. "The attack breaks a couple of security checks introduced to Java SE by Oracle over the recent months (issues 57 and 58)," he said. "It also exploits code fragments that were missing proper security checks corresponding [in] mirror code (issue 59 and 60). Finally, it demonstrates a difference between the JVM specification and its implementation (issue 56)." His "issue" numbers refer to individual bugs that he's discovered in Java, beginning last year.

Gowdiak said detailed information on the vulnerabilities and proof-of-concept exploit code was submitted Monday to Oracle. He told Softpedia that the vulnerabilities are still present in Java 7 update 17.

Gowdiak said he discovered the new vulnerabilities after Oracle dismissed one of his previous bug notifications (issue 54) -- which was used as part of a sandbox-bypassing attack against Java 7 update 15 -- as being "allowed behavior," which led him back to Oracle's Java documentation. "We confirmed that company's initial judgment of issue 54 as ... 'allowed behavior' contradicts both Java SE documentation as well as existing security checks in code," he said. "It looks Oracle needs to either start treating issue 54 as a vulnerability or change the docs and relax some of the existing security checks."

Of the five vulnerabilities, two might also affect Java 6, although Gowdiak said that he didn't confirm that, owing to Oracle having officially retired Java 6 last month, at which point the company had said it would cease to update Java 6. Gowdiak said that all five of the new bugs he's discovered must be used together for the new exploit to work. Accordingly, he said, "we treat it as affecting Java SE 7 only."

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