After nearly a week of silence from Oracle, the company today quietly pushed out a Java update that closes the holes being exploited by attackers in the latest Java exploit.

Oracle's release today of Java Version 7 Update 7 came unexpectedly in the wake of the recent attacks, which were based on flaws in the software that a group of researchers say they first reported to Oracle six months ago. Security researchers who have been studying and following the spread of the exploit today confirmed the update does the trick and halts the exploit.

"We've tested it, and it appears to be effective," says Marcus Carey, a security researcher with Rapid7, which had released a Metasploit exploit for the attack this week. "If [enterprises] absolutely need Java, they should test that it works with their existing software and upgrade this ASAP. But the average user should patch it, for sure -- [but] most people don't need the Java plug-in, to be honest."

The Java exploit, originally used for targeted attacks, went public last week and began to spread like wildfire after it was added to the popular BlackHole crimeware kit, making it easily accessible to all types of cybercriminals. Researchers -- who described the attack as very reliable -- saw some 100 domains hosting the exploit and tens of thousands of infected host machines as of yesterday.

Initial reports cited a single zero-day flaw being exploited, but a researcher for Immunity Inc. discovered that the weaponized attack was based on two zero-day exploits. "When working our way through each step this exploit performed, we realized there were two different bugs chained together, cleverly used in order to exploit a target," and only worked when exploited in tandem, Immunity researcher Esteban Guillardoy told Dark Reading.

Meanwhile, Symantec says some of the attackers employing the Java attack are the so-called Nitro gang, which were spotted targeting chemical companies last fall. "The attackers have escalated their efforts, however. As discussed in our previous blog, a new Java zero-day vulnerability has been seen being exploited in the wild. We can confirm that some of the attackers behind this round of attacks are actually the Nitro gang," Symantec blogged today.

Oracle was not available for comment at the time of this posting.

Andrew Storms, director of security operations at nCircle, says the Oracle's technical note about the patch credits Security Explorations, the firm that reported the bug in April.

Immunity today conducted a quick analysis of the patch and found that it not only fixes the so-called CVE-2012-4681 flaws, but also two other flaws in Java. "This seems to be a new move in the recent history of Java updates, since generally it takes months to QA a Java security bug fix -- which may be how long this took, considering some researchers claim they sent these vulnerabilities to Oracle months ago," says Immunity's Nico Waisman in a blog post today.

"While doing some fast analysis (keep in mind we only spent an hour and half on it), we find out that they patched at least 4 vulnerabilities in the Java code base: The two used by the Gondvv worm and two more on difference pieces of code. Just by simply running the Immunity CANVAS exploit that exploits this vulnerability we can see that this update is preventing it," Waisman says.

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