SSL Hole Plugged (supposedly)
PerfectReign
http://www.theregister.co.uk/2009/11/05/serious_ssl_bug/
Researchers say they've uncovered a flaw in the secure sockets layer
protocol that allows attackers to inject text into encrypted traffic
passing between two endpoints.
The vulnerability in the transport layer security protocol allows man-in-
the-middle attackers to surreptitiously introduce text at the beginning
of an SSL session, said Marsh Ray, a security researcher who discovered
the bug. A typical SSL transaction may be broken into multiple sessions,
providing the attacker ample opportunity to sneak password resets and
other commands into communications believed to be cryptographically
authenticated.
Practical attacks have been demonstrated against both the Apache and
Microsoft IIS webservers communicating with a variety of client
applications. A consortium of some of the world's biggest technology
companies have been meeting since late September to hash out a new
industry standard that will fix the flaw. A draft is expected to be
submitted on Thursday to the Internet Engineering Task Force.
"A core security guarantee made by TLS is violated as a result of this
problem," said Steve Dispensa, CTO of PhoneFactor, a provider of two-
factor authentication services, the company where Ray works. "It's going
to take a while for the protocol changes necessary to be rolled out,
because every browser and every server in the world is going to have to
be patched."
Ray and Dispensa were quick to note that the vulnerability would most
likely have to be exploited in concert with some other security weakness,
say a flaw in a home router or the recent DNS bugs discovered by
researcher Dan Kaminsky. And even then, an attacker would be unable to
read encrypted data that flowed between a server and a client.
Indeed, Moxie Marlinspike a security researcher who has repeatedly
exposed serious shortcomings in SSL, said the attacks were hard to pull
off in the real world, in large part because they appeared to target a
rarely used technology known as client certificate authentication.
"It's clever, but to my knowledge the common cases in which the majority
of people use SSL (webmail, online banking, etc.) are currently
unaffected," he wrote in an email. "I haven't found these attacks to be
very useful in practice."
But Ray and Dispensa said there are attacks that don't rely at all on
client authenticated certificates. They maintained that the ability of an
attacker to inject plaintext of his choice into an authenticated data
stream represented a major threat. And they said the attack has special
implications for smartcards and other technologies that rely on client
authenticated certificates.
"There is consensus among the biggest vendors in the world that it's a
big problem," Dispensa said.
Already, developers from OpenSSL and GNU TLS have developed patches and
are in the process of testing them. Other providers of hardware and
software that implement SSL are in various stages of patching as well.
Dispensa and Ray presented their findings under a non-disclosure
agreement to a large number of company representatives on September 29 in
Mountain View, California, at a company they declined to name.
The parties had planned to continue working on a fix in secret throughout
the rest of the year. Coincidentally, a separate researcher recently
documented the basics of the protocol defect and made some of the
findings public, prompting Ray to disclose his research. The flaw has
existed in TLS since the specification was published in the mid 1990s.
The vulnerability stems from the ability for either party in an SSL
transaction to renegotiate the session, usually so one or the other can
refresh its cryptographic keys. Because HTTP lacks a way to direct the
client to resubmit the request within a newly authenticated channel, the
server must apply the authentication retroactively.
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