By Robert McMillan
IDG News Service
February 23, 2007
Google's PC search software is vulnerable to a variation on a
little-known Web-based attack called anti-DNS pinning that could give an
attacker access to any data indexed by Google Desktop, security
researchers said this week.
This is the second security problem reported this week for the software.
On Wednesday, researchers at Watchfire said they'd found a flaw that
could allow attackers to read files or run unauthorized software on
systems running Google Desktop.
As with Watchfire's bug, attackers would first need to exploit a
cross-site scripting flaw in the Google.com Web site for this latest
attack to work, but the consequences could be serious, according to
Robert Hansen, the independent security researcher who first reported
the attack. "All of the data on a Google desktop can now be siphoned off
to an attacker's machine," he said.
Cross-site scripting flaws are common Web server vulnerabilities that
can be exploited to run unauthorized code within the victim's browser.
Hansen, who is CEO of Sectheory.com, did not post proof of concept code
for his attack, but he said that he has "tested every component of it,
and it works." He has posted some details of how Google Desktop data
could be compromised on his blog.
Google said it was investigating Hansen's findings. "In addition, we
recently added another layer of security checks to the latest version of
Google Desktop to protect users from vulnerabilities related to Web
search integration in the future," the company said in a prepared
Anti-DNS pinning is an emerging area of security research, understood by
just a handful of researchers, said Jeremiah Grossman, CTO at WhiteHat
Security. The variation of this attack described by Hansen manipulates
the way the browser works with the Internet's DNS in order to trick the
browser into sending information to an attacker's computer.
"Once you can re-point Google to another IP address, instead of Google
getting the traffic, the bad guy does," he said.
Because this type of attack is so difficult to pull off and is poorly
understood, it is unlikely to be used by the criminals any time soon,
Grossman said. But anti-DNS pinning shouldn't be ignored, he added. "We
should keep our eyes on it in case the bad guys shift gears."
News of the attack comes as Google is trying to enter the desktop
productivity market. On Thursday, Google launched a suite of Web-based
collaboration software, called the Google Apps Premier Edition, that
analysts say could become a competitor to Microsoft Office.
The troubling thing about the attack Hanson identified, which he calls
anti-anti-anti-DNS pinning, is that there is very little that can be
done to avoid it short of eliminating cross-site scripting
vulnerabilities on the Web.
"This is really just fundamentally about how browsers work," he said.
"If you allow a Web site to have access to your drive -- to modify, to
change things, to integrate, or whatever -- you're relying on that Web
site to be secure."
Hansen and Grossman say that Google is not the only company vulnerable
to a growing category of Web-based attacks. For instance, MySpace.com
was hit when a fast-moving worm spread through the MySpace community in
early December, stealing MySpace log-in credentials and promoting adware
"A lot of these new attack techniques are going to require the browsers
to improve," Grossman said. "The users really have very little ability
to protect themselves against these attacks" he said. "It's very bad.
Even the experts are afraid to click on each other's links anymore."
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