New research dissecting the initial exploit and malware used in the attack against RSA concludes that Windows' Data Execution Prevention (DEP) would have halted the attack if the victims were on Windows 7 machines.

DEP, which is built into Windows 7 and is available for Vista and XP SP2, would have stopped the exploit in its tracks, said Rodrigo Rubira Branco, director of Qualys' Vulnerability & Malware Research Labs, who tested the exploit and published his results Wednesday. He said it appears that the EMC RSA victims were running XP and did not have DEP enabled on their systems.

"The victims were using Windows XP, which is DEP-capable since SP2. I know that for sure because the exploit won't work against Windows 7 due to limitations in the exploit code itself," Branco said. "In this specific case, it was possible to change the exploit to work against DEP, but the exploit has been likely reused from another target. Having DEP on would prevent the exploitation.

"We can't say that the attacker would not change the exploit and try again, but it clearly was going to give more time to the defense to detect the attack and mitigate its effects."

Researchers have demonstrated bypassing DEP in older versions of Windows. Branco said the exploit demonstrates how even using patched, older technologies can leave an organization vulnerable. "If you use old technologies, even when they are patched, they are more exposed since the prevention mechanisms are not there, and when they are, they are easily bypassed," he said.

Branco, who published his research Wednesday in a blog post, said digging into the original phishing email and rigged Excel attachment helped confirm the theory that the attackers wanted access to U.S. military contractors, not RSA itself.

RSA has said publicly that its breach was a means to an end for the attackers. "We were a path to try to attack other organizations," said Eddie Schwartz, CSO for EMC RSA. "That was very clear just based on other things we've subsequently learned from the attack."

And F-Secure, which was the first to find the RSA email on VirusTotal, believes the attackers needed RSA SecurID tokens to get into Lockheed-Martin and Northrop Grumman.

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