Oracle today issued an emergency update to patch the critical vulnerabilities hackers have been using in increasing numbers to hijack Windows PCs.

According to Rapid7, the security firm that maintains the Metasploit open-source penetration framework, the so-called "out-of-band" update will stymie the current attack campaigns.

"It appears that it's effective in blocking the exploit," Tod Beardsley, the engineering manager for Metasploit, said early Thursday. "We just finished testing it 10 minutes ago."

Oracle posted the update -- designated "1.7.0_07-b10" -- published a bare-bones release note on its website, and followed that with an alert shortly after 1 p.m. ET listing the three security vulnerabilities addressed and a single defense-in-depth change it included.

The company also posted a short blog entry on the update.

Hackers had been exploiting two of the bugs for some time in targeted attacks, but in the last several days the scale of those campaigns had dramatically increased.

Adam Gowdiak, the founder and CEO of Polish security firm Security Explorations, who in early April reported the vulnerabilities, also confirmed that Thursday's Java update shuts down the in-use exploits.

"None of the original code that we sent to Oracle in April 2012 can be used to achieve a complete Java security sandbox bypass [after the update is applied]," said Gowdiak in an email reply to questions.

Yesterday, the IDG News Service, which like Computerworld is operated by IDG, reported that Gowdiak had told Oracle of the exploited flaws four months ago, on April 2.

Oracle did not give Gowdiak a heads-up that it would be shipping an out-of-band update today. "[But] we expected that they would do this, taking into account the recent events surrounding the 0-day attack code and the widespread surprise that the serious security flaws we reported to the company in April 2012 had not been addressed earlier," said Gowdiak.

Gowdiak, Beardsley and others also commented on the unusual nature of an emergency update from Oracle.

"If we assume that they heard about [the vulnerabilities] the same time they went public, then getting a patch out in four days was lightning quick," said Beardsley. "And if the rumor is true that they've had it for several months, it's still pretty quick for them ... they usually take six months or more."

Andrew Storms, director of security operations at nCircle Security, also applauded Oracle's speed. "Let's give them a little credit and say they delivered the patch in about a week of it going public," said Storms. "I'd say not bad on the turn-around, [so] hat tip to the dev team."

Gowdiak agreed. "We are glad that Oracle didn't wait with the update till October," he said, referring to the next regularly-scheduled Oracle patch date of Oct. 16. "We hope that out-of-band patches will become more common and will be used whenever a need arises to protect users of Oracle software."

But Storms blasted Oracle's communication skills. "Talk to the hand for the [security] PR team," he said. "Oracle is so horrible at security PR, unless they want to let you know that their products are supposedly unbreakable."

Until today, Oracle had refused to comment on the bugs or the in-the-wild exploits.

Users can obtain the emergency update from Oracle's website.

Lucian Constantin, of the IDG News Service, contributed to this report.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is gkeizer@computerworld.com.

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