Researcher releases attack code for just-patched Windows bug

Microsoft fixed flaw nine months after it was revealed at last year's Pwn2Own hacking contest

Attack code for a Windows vulnerability that Microsoft patched last week was released by a researcher one day after the company fixed the flaw.

The bug, which Microsoft rated "critical" -- its highest threat ranking -- was first reported more than nine months earlier when its discoverer used it in a one-two punch against Internet Explorer 8 (IE8) that won him $10,000 in a hacking challenge.

Peter Vreugdenhil, then an independent Dutch researcher but now employed by HP TippingPoint, the sponsor of the Pwn2Own contest, used the vulnerability to sidestep one of Windows 7's most important anti-exploit defenses, ASLR (address space layout randomization).

"I used this to get rid of ASLR, and another vulnerability to bypass DEP," said Vreugdenhil in an interview today. DEP, or data execution prevention, is another protection technology that Microsoft relies on to make it difficult for attackers to execute their malicious code on Windows.

When Vreugdenhil hacked IE8 in under two minutes at last year's Pwn2Own, TippingPoint's Aaron Portnoy called it "technically impressive."

"There were a multitude of reasons why it was so impressive," said Portnoy, the manager of TippingPoint's security research team. "One was the fact that he used two vulnerabilities, each likely exploitable on their own, in tandem. Peter got them to work together."

Vreugdenhil posted one version of the exploit he used at Pwn2Own on his own Web site last Wednesday. That was the day after Microsoft patched the vulnerability in Microsoft Data Access Components (MDAC), a set of components that lets Windows access databases such as Microsoft's own SQL Server. The flaw is in the MDAC ActiveX control that allows users to access databases from within IE.

The attack code may not be much good to criminals as is, said Vreugdenhil, who used later versions of the exploit at the contest.

"It's probably not going to work if you just run it," Vreugdenhil said. "It's more likely that [IE] will crash [because] it's not as reliable as what I used at Pwn2Own."

Although Microsoft fixed Vreugdenhil's other vulnerability in June, it took more than nine months to issue a patch for the MDAC bug he used in the contest.

Portnoy blamed miscommunication and a tracking problem on Microsoft's part for the delay.

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