Vendors team up to patch deficiencies in the protocol used by the Domain Name System that can be exploited to poison DNS caches and redirect user traffic on the Internet.A number of vendors have teamed up to solve a serious flaw inherent in the
Domain Name System that could allow an attacker to redirect Internet traffic.
The flaw in the DNS, an Internet service that translates domain names into
IP addresses, was uncovered by security researcher Dan Kaminsky, director of
penetration testing for IOActive.
During a press briefing July 8, Kaminsky was mum about specific technical
details of the vulnerability, but said the problem has been solved by
implementing port randomization. Rather than randomizing on an ID transaction
field of 16 bits, it will now randomize using 27 to 30 bits, he said.
According to officials at the ISC (Internet Systems Consortium), the DNS
protocol uses the Query ID field to match incoming responses to previously sent
queries. The Query ID field is only 16 bits, however, and in the scenario
discovered by Kaminsky, that is not random enough to prevent easy exploitation,
ISC officials said in a statement.
"It's the kind of a flaw that would allow an attacker to, say … go
after your ISP, and if somebody dialed in, or wanted to go to Google.com, they
could redirect them to pretty much any place they wanted," Rich Mogull of
security consulting company Securosis said during the briefing.
So far, there have been no attempts to exploit the vulnerability in the
wild, according to Kaminsky, who added that more information will be released
in the next 30 days to help businesses better protect themselves.
"Design bugs are interesting in that they don't just constrain
themselves to an individual company, an individual implementation,"
Kaminsky explained. "Because the system is behaving exactly like it's
supposed to behave, the same bug will show up in vendor after vendor after
vendor … this one flaw that I had found, this one issue I had found, actually
affected not just Microsoft,
not just ISC BIND, not just Cisco, but everybody."
The flaw was uncovered six months ago. On March 31, 16 researchers from around the world
met to come up with a solution to the problem, and agreed to coordinate the
release of a patch across all platforms.
"Our primary focus is on DNS servers, because the
vulnerability is primarily a server vulnerability," Kaminsky said.
"There are scenarios in which not just DNS servers, but all the little
clients out there that happened to use DNS, there are scenarios in which those
hosts can be vulnerable as well. It's not the focus; they are not universally
vulnerable. But there are patches that are out now or may be coming that will
handle those clients."
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