Major internet flaw worse than feared

August 8, 2008 - 11:41AM

A newly discovered flaw in the internet's core infrastructure not only
permits hackers to force people to visit websites they didn't want to,
it also allows them to intercept email messages, the researcher who
discovered the bug said.

Considering the silent nature of the attack and the sensitive nature
of a lot of electronic correspondence, the potential for damage from
this second security flaw is high. But there's no evidence yet that
this method of targeting e-mail has been used in a successful attack.

Dan Kaminsky of Seattle-based security consultant IOActive exposed a
giant vulnerability in the internet's design that, in one case,
allowed hackers to reroute some computer users in Texas to a fake
Google.com site loaded with automated advertisement-clicking programs,
a scam to generate profits for the hackers from those clicks.

The flaw wasn't in the site itself, it was in the back-end machines
responsible for guiding computers to that site.

The vulnerability Kaminsky found is especially insidious because it
allows criminals to tamper with machines whose reliability and
trustworthiness is critical for the internet to function properly.

Kaminsky, who spoke on Wednesday at the Black Hat hacker conference in
Las Vegas, has given few details publicly about the vulnerability he
found in the Domain Name System (DNS), a network of servers used to
connect computers to websites.

He remained tightlipped so that internet providers would have time to
fix their machines. Many have done that, but others have delayed,
leaving some people at risk.

Major vendors like Microsoft, Cisco Systems, Sun Microsystems and
others have issued patches - software tweaks that cover the security
hole and prevent affected machines from ingesting the bogus
information hackers are trying to feed them.

"The industry has rallied like we've never seen the industry rally
before," Kaminsky said.

Kaminsky's talk at the conference was packed, with people sitting on
the floor of the main speaker's hall and overflowing out the back
doors. His presentation instantly became one of the Black Hat
conference's most anticipated after he announced on July 8 that he'd
found a major weakness in DNS, a critical part of the internet's
plumbing.

While some details leaked out early - security researchers accurately
guessed parts of Kaminsky's discovery - he was able to keep a few
juicy bits secret until the talk.

One of those was the susceptibility of many email servers to the DNS
vulnerability, an opening that gives criminals a way to plant
themselves in the middle of the transmission from the sender to the
recipient and redirect messages to their own servers, Kaminsky said.

The result: criminals have a way not only to comb through the contents
of those messages, but also to gain access to other password-protected
websites the victims belong to.

That's because most sites have a feature that allows members to
retrieve their passwords by email if they've forgotten them. If a
criminal has access to the account where that message is sent, he can
then begin snooping on the contents of that account, from e-mail, to
banking, to retailer sites.

The thrust of the DNS flaw is that it allows hackers to attach bad
information to packets flowing in and out of DNS servers so they
change the directions they give to certain websites.

It's the equivalent of turning around a street sign to send drivers
down the wrong street.

So someone who innocently types in the address of a legitimate website
can be strong-armed instead into going to a malicious site under the
criminal's control. Because the attack happens at the network level,
and the browser believes it's visiting the legitimate site, the attack
is nearly impossible for users to detect.

Many email servers are vulnerable because they also handle DNS
traffic, Kaminsky said. Even if they only handle internal inquiries,
if they interact with external DNS servers, that's often enough to
expose them to attack.

Hackers are thus able to manipulate the packets associated with email
traffic the same way they manipulate the packets associated with
general web traffic.

AP



http://www.smh.com.au/news/security/major-internet-flaw-worse-than-feared/2008/08/08/1218139041485.html

-- 
"I not only use all the brains that I have, but all that I can
borrow." Woodrow Wilson

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