Disclosure of Java zero-day prompted Oracle patch, says researcher

Oracle released an emergency patch on Thursday for previously unknown Java vulnerabilities that cybercriminals had targeted with popular exploit kits within hours after the bugs' existence became public.

The patch for the critical flaws that affected only Java 7, the latest version of the software platform, also included fixes for two other vulnerabilities in Java 6. But the Java 7 flaws, which became known publicly on Sunday, were the most critical.

"Due to the severity of these vulnerabilities, the public disclosure of technical details and the reported exploitation of CVE-2021-4681 in the wild, Oracle strongly recommends that customer apply the updates provided by this security alert as soon as possible," the company said.

[See also: 10 ways to secure browsing in the enterprise]

The vulnerabilities affected all the major web browsers running Java 7, including Google Chrome, Microsoft Internet Explorer, Apple Safari and Mozilla Firefox. Chrome was less vulnerable because by default, it asks users before running a Java applet, giving them the opportunity to block a malicious install.

In general, a cybercriminal could exploit the bugs by tricking a victim into clicking a malicious link on a hijacked Website or a site run by the attacker.

Debate over disclosure continues

The quickness with which cybercriminals exploited the vulnerabilities has raised questions about whether researchers' disclosure of the flaws put more computer users at risk than necessary.

Some security vendors knew about the vulnerabilities for weeks, but chose not to make them public because the number of attacks was small. Until the vulnerabilities became widely known, Sophos saw attacks targeted at specific industries, affecting only hundreds of people, Chester Wisniewski, senior security adviser for the vendor, said.

Once the flaws became public, the number of potential victims grew to hundreds of millions, given Secunia estimates of a billion computers running Java 7.

The public disclosure of the flaws started when FireEye reported in a blog post that cybercriminals were exploiting an unpatched Java vulnerability. While the vendor did not provide complete details for the flaw, there was enough information for Joshua Drake, a security researcher from Accuvant, to build a proof of concept of an exploit with the help of Rapid7.

Within six hours after that proof of concept was posted on the web, cybercriminals had updated exploit kits, including the popular Blackhole, in order to infect vulnerable computers with malware.

Tod Beardsley, a bug testing engineering manager for Rapid7, said the company was justified in going public with the flaws, because cybercriminals were already exploiting them.

"I certainly don't think that we would have seen a patch from Oracle on Thursday if we had kept it under wraps," Beardsley said. "It was already exploited out there, so I don't think we ran afoul of any disclosure stuff."

In general, security researchers do not reveal unexploited vulnerabilities until after notifying the software vendor and giving it time to fix them. "Once its out in the wild, the cat's out of the bag at that point," Beardsley said.

Wisniewski was not comfortable with Rapid7's handling of the disclosure, saying, "I'm really torn." Because the number of hacker-devised exploits is so widespread now, many more people will be vulnerable. Rapid7's own estimates are that roughly a third of Java users fail to remain up to date on patches.

"The people who published all the information drew a roadmap on how to exploit people," Wisniewski said. "That negative outweighs any benefit of us getting a patch out of Oracle a couple of months early."

Oracle is partly to blame for the disclosure because it refuses to work closely with researchers and won't discuss when or if it will release patches, Wisniewski said. "Oracle does not have the best track record of releasing updates in a timely manner, and that makes security researchers more apt to publish these things."

Oracle, which did not respond to a request for comment, had known about the Java 7 flaws since April, according to Adam Gowdiak, the founder and chief executive of Polish security firm Security Explorations. Gowdiak said he notified Oracle of 19 Java 7 issues, including the two critical flaws.

Attackers are increasingly targeting Java vulnerabilities, because the cross-platform runtime environment is typically on Linux, Windows and Mac computers. Experts have said the risk to users could grow if Oracle doesn't do more to secure the product.

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