By Robert McMillan
IDG News Service
10 July 2008
Computer security professionals have ganged up on Dan Kaminsky for
violating a cardinal rule of hackerdom: publicising a flaw without
providing the technical details to verify the finding.
Kaminsky made headlines earlier this week by talking about a major flaw
in the DNS software used to connect computers to each other on the
Internet. In late March he grouped together 16 companies that make DNS
software - companies like Microsoft, Cisco and Sun Microsystems - and
talked them into fixing the problem and jointly releasing patches for
On Wednesday this week, he took things a step further on his blog,
asking hackers to avoid researching the problem until next month, when
he plans to release more information about it at the Black Hat security
He said he wanted to go public with the issue to put pressure on
corporate IT staff and Internet service providers to update their DNS
software, while at the same time keeping the bad guys in the dark about
the precise nature of the problem. A full public disclosure of the
technical details would make the Internet unsafe, he said. "Right now,
none of this stuff needs to go public."
He quickly received a sceptical reaction from Matasano Security
researcher Thomas Ptacek, who blogged that Kaminsky's cache poisoning
attack is merely one of many disclosures underlining the same well-known
problem with DNS -- that it does not do a good enough job in creating
random numbers to create unique "session ID" strings when communicating
with other computers on the Internet.
"The bug in DNS is that it has a 16-bit session ID," he said via an
e-mail Wednesday. "You can't deploy a new Web app with less than 128-bit
session IDs. We've known about that fundamental problem since the '90s."
"Here comes the onslaught of interviews and media explosion for another
overhyped bug by Dan Kaminsky," wrote a jaded (and anonymous) poster to
the Matasano blog.
Over at the SANS Internet Storm Center, one blogger speculated that
Kaminsky's bug had actually been disclosed three years earlier.
The flaw appears to be a serious one that could be exploited in what's
called a "cache poisoning attack". These attacks hack the DNS system,
using it to redirect victims to malicious websites without their
knowledge. They have been known about for years but can be hard to pull
But Kaminsky claims to have found a very effective way of launching such
an attack, thanks to a vulnerability in the design of the DNS surprised"
by some of the negative reaction, but that this kind of scepticism was
vital to the hacker community. "I'm breaking the rules," he admitted.
"There's not enough information in the advisory to figure out the attack
and I'm bragging about it."
According to DNS expert Paul Vixie, one of the few people who has been
given a detailed briefing on Kaminsky's finding, it is different from
the issue reported three years ago by SANS. While Kaminsky's flaw is in
the same area, "it's a different problem", said Vixie, who is president
of the Internet Systems Consortium, the maker of the most widely used
DNS server software on the Internet.
The issue is urgent and should be patched immediately, said David Dagon,
a DNS researcher at Georgia Tech who was also briefed on the bug. "With
sparse details, a few have questioned whether Dan Kaminsky had
repackaged older work in DNS attacks," he said. "It is not feasible to
think that the world's DNS vendors would have patched and announced in
unison for no reason."
By day's end, Kaminsky had even turned his most vocal critic, Matasano's
Ptacek, who issued a retraction on this blog after Kaminsky explained
the details of his research over the telephone. "He has the goods,"
Ptacek said afterward. While the attack builds on previous DNS research,
it makes cache poisoning attacks extremely easy to pull off. "He's
pretty much taken it to point and click to an extent that we didn't see
Kaminsky's remaining critics will have to wait until his 7 August Black
Hat presentation to know for sure, however.
The security researcher said he hopes that they show up for his talk.
"If I do not have the exploit," he said. "I deserve every single piece
of anger and distrust."
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