Researchers Stymied By Microsoft Vulnerability

Mike Murray, the director of research at vulnerability management vendor nCircle, has had his entire team picking through the patch provided by Microsoft to fix a flaw in Windows' SMB (Server Message Block) protocol, and hasn't yet been able to find a way to exploit the vulnerability without going through authentication.

"It's incredible," said Murray. "We've found all the functions and the overflow, but we haven't been able to find the unauthenticated [attack] vector. We've found the authenticated vector, but as for the other, nope."

nCircle pulls apart disclosed vulnerabilities to create new methods of vulnerability detection, and in the short term, to provide guidance to its customers on the relative danger of flaws in applications and operating systems, including Windows.

According to Microsoft, the SMB vulnerability, which was laid out in one of the ten security bulletins released Tuesday, could be exploited remotely by an attacker without requiring authentication, in other words, without a legitimate Windows log-in username and password.

Such an unauthenticated attack avenue, experts warned Tuesday, made the bug much more dangerous, and could lead to a worm-style assault that attacked any computer with the SMB service exposed to the Internet.

"There's a trick to this one," said Murray. When asked if it was good news that his team couldn't find the exploit -- that if they couldn't perhaps attackers might not either -- he said "It only takes one person to figure out that trick, and then it'll break wide open."

Even though the nCircle research team has so far failed to puzzle out the SMB vulnerability, Murray still thinks that it's the most dangerous of the 12 announced yesterday.

"It's still the most threatening, by far," said Murray. "In fact, there are two vulnerabilities, not just one," he said. "[The second] is strictly a denial-of-service vulnerability, a way to crash the SMB service through an uninitialized variable. Maybe Microsoft missed it, or didn't think of it as a true vulnerability, since it was the [buffer] overflow they concentrated on."

Murray said his bunch would continue examining the vulnerability until they found a way to hack SMB sans authentication. "This is a tough nut to crack," he admitted. "Or maybe Microsoft was just throwing us a red herring telling us that it could be exploited unauthenticated."