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By | Robert Lemos 4th August 2006 09:03

Attackers pass on operating systems

Aim for drivers and apps instead

The disappearance of easy-to-find flaws in the major operating systems has pushed vulnerability researchers to branch out from finding security issues in core system software and instead concentrate on the device drivers and client-side agents present on all PCs, security experts said on Wednesday at the Black Hat Briefings.

During a presentation, two vulnerability researchers from security firm Matasano presented the results of their research on the common software agents included on many enterprise computer systems.

The two researchers, David Goldsmith and Thomas Ptacek, found numerous vulnerabilities in the agents designed to handle automatic updating, schedule backup tasks and handle support requests, the researchers said.

In another presentation, two other researchers - SecureWorks flaw finder David Maynor and graduate-student-cum-hacker "johnny cache" - showed off a method of compromising laptop computers via flaws in the wireless drivers. In a movie demonstrating the technique, the duo showed the attack compromising an Apple MacBook, allowing Maynor the ability to create and delete files on the desktop.

The two research projects underscore the move away from finding flaws in the operating system, Maynor said.

"Now that the OS layer is harder to crack, you are seeing a lot more people going higher up the stack, to applications, or lower, to device drivers," Maynor said.

The trend is not just evident at the Black Hat Briefings. Last year, Maynor investigated a variety of device drivers in Windows XP and Linux, finding numerous flaws. Other researchers have focused on Bluetooth drivers, in one case finding lax passwords allowed hackers to eavesdrop on the audio signals from passing cars.

Common applications and software agents are also garnering more attention. Flaw finders and attackers bent on industrial espionage have started focusing on discovering vulnerabilities in Microsoft Office. For the past 18 months, researchers have also focused on finding security issues in the antivirus clients that ironically are supposed to protect PCs from attacks. And, researcher HD Moore used data-fuzzing tools to find numerous flaws in the most common browsers used by web surfers.

Many of the vulnerabilities are easy to find and should have been caught by developers, if the companies had performed a basic security audit, said Matasano's Ptacek.

"The amazing thing is that the vulnerabilities we found were simple, they were 1993 vulnerabilities," he said. "These have clearly not been looked at before. We are talking straight-up stack overflows-the first thing that someone would test for if they were doing an audit."

Ptacek and Goldsmith found numerous simple vulnerabilities in the common applications included on many enterprise and consumer PCs to handle various automated maintenance chores. While the duo would not name the specific applications or the issues, they said they were common and pervasive.

"Your Dell is running five of these things," Ptacek said. "Your server is running five more. They are bots, helper bots, but they are just waiting to be taken over."

Matasano already has 30 vulnerability reports waiting to be published after the software developers fix the issues.

However, the fixes might not come too soon, said Goldsmith. The companies that program the various software agents typically do not have a security process, he said.

"The vendors are not prepared to deal with a vulnerability report. In many cases, there is no security contact."

While Apple has frequently been criticised by security researchers over the difficulty many flaw finders have found in reporting vulnerabilities to the company, the Mac maker responded quickly to the report filed by Maynor and "johnny cache," the duo said.

The duo found they could fingerprint more than a dozen wireless chips and their associated firmware just by eavesdropping on the wireless traffic. Using the information and a database of driver flaws found by a homegrown data-fuzzing tool, Maynor and "johnny cache" could compromise not just a MacBook but also Linux and Windows XP laptops, the duo claimed.

"While we attacked an Apple, the flaws are not in the Mac OS X operating system but in the hardware device drivers," Maynor told SecurityFocus.

On Wednesday, Intel released a major fix for vulnerabilities in its Centrino wireless drivers. The massive fix was about "the size of a Windows service pack," Maynor said, and was not related to the Black Hat presentation.

The fuzzing techniques used by the pair of researchers discovered mostly flaws that could be used to cause a denial-of-service. Only a few flaws could be exploited to compromise a computer system.

"It is a very high crash-to-exploitable ratio," Maynor told SecurityFocus. "There are a lot of things in the 802.11 stack that can lead to a blue screen rather than an exploitable condition."

The two researchers did not show off the Apple MacBook exploit live at the conference, but in a video of the actual attack. They worried that security researchers could sniff the attack and duplicate it.

Tipping off attackers is a worry for Matasano's Ptacek and Goldsmith as well. The two avoided mentioning specifics about the software agents they audited or the PC makers affected by the vulnerabilities. Both cases signal a race between the software vendors and would-be attackers that might use the techniques, said Ptacek.

"Attackers have not heard about this stuff yet," he said. "When that changes, it is a worry, because it's so simple to find these flaws."

This article originally appeared in Security Focus.

Copyright © 2006, SecurityFocus

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