Broadband Advisor

A computer security company on Monday inadvertently published details of a major flaw in the Internet's Domain Name System (DNS) several weeks before they were due to be disclosed.

The flaw was discovered several months ago by IOActive researcher Dan Kaminsky, who worked through the early part of this year with Internet software vendors such as Microsoft, Cisco and the Internet Systems Consortium to patch the issue.

The companies released a fix for the bug two weeks ago and encouraged corporate users and Internet service providers to patch their DNS systems as soon as possible. Although the problem could affect some home users, it is not considered to be a major issue for consumers, according to Kaminsky.

At the time he announced the flaw, Kaminsky asked members of the security research community to hold off on public speculation about its precise nature in order to give users time to patch their systems. Kaminsky had planned to disclose details of the flaw during a presentation at the Black Hat security conference set for Aug. 6.

Some researchers took the request as a personal challenge to find the flaw before Kaminsky's talk. Others complained at being kept in the dark about the technical details of his finding.

On Monday, Zynamics.com CEO Thomas Dullien (who uses the hacker name Halvar Flake) took a guess at the bug, admitting that he knew very little about DNS.

His findings were quickly confirmed by Matasano Security, a vendor that had been briefed on the issue.

"The cat is out of the bag. Yes, Halvar Flake figured out the flaw Dan Kaminsky will announce at Black Hat," Matasano said in a blog posting that was removed within five minutes of its 1:30 p.m. Eastern publication. Copies of the post were soon circulating on the Internet, one of which was viewed by IDG News Service.

Matasano's post discusses the technical details of the bug, saying that by using a fast Internet connection, an attacker could launch what's known as a DNS cache poisoning attack against a Domain Name server and succeed, for example, in redirecting traffic to malicious Web sites within about 10 seconds.

Matasano Researcher Thomas Ptacek declined to comment on whether or not Flake had actually figured out the flaw, but in a telephone interview he said the item had been "accidentally posted too soon." Ptacek was one of the few security researchers who had been given a detailed briefing on the bug and had agreed not to comment on it before details were made public.

Matasano's post inadvertently confirmed that Flake had described the flaw correctly, Ptacek admitted.