PDF files put Windows XP at risk

Published 24 September 2007

Cybersecurity researcher says vulnerabilities in popular Adobe file format allows hackers to seize control of computers; Adobe, Symantec work on solution

A British security researcher last week disclosed two critical flaws in popular media files, and on Friday said that a zero-day vulnerability in Adobe’s pervasive PDF files could be exploited to seize control of Windows XP systems. Petko Petkov, a penetration tester who disclosed a zero-day flaw in Apple’s QuickTime a week ago and a similarly critical bug in Microsoft’s Windows Media Player on Tuesday, now says that Adobe System’s Acrobat Reader files harbor a serious vulnerability. The PDF zero-day beats the media file flaws hands down, said Petkov. “Adobe Acrobat/Reader PDF documents can be used to compromise your Windows box,” he said on his blog today. “Completely!!! Invisibly and unwillingly!!! All it takes is to open a PDF document or stumble across a page, which embeds one.”

Computerworld’s Gregg Keizer reports that in the QuickTime and Windows Media Player cases, Petkov posted proof-of-concept exploit code, but did not do so for Adobe Acrobat. He explained the reasons for his refusal to publish code to prove that the PDF vulnerability is real: “The issue is quite critical given the fact that PDF documents are in the core of today’s modern business,” Petkov wrote. “This and the fact that it may take a while for Adobe to fix their closed source product are the reasons why I am not going to publish any POCs [proof-of-concepts]. You have to take my word for it. The POCs will be released when an update is available.” Petkov provided no proof of his claim, but security company Symantec believes his claims. “Although these claims are currently unverifiable, this researcher has identified several vulnerabilities in the past and is likely credible regarding these findings,” the company said in an alert to customers of its DeepSight threat network.

My advise [sic] for you is not to open any PDF files (locally or remotely),” Petkov said. Petkov said he had tested and verified that the vulnerability exists in the most recent version of Acrobat Reader, Version 8.1, and can be exploited on PCs running Windows XP SP2. The bug would not be the first found in Adobe’s PDF file format or the software which creates and displays them. In January, for example, Adobe updated Reader and Acrobat to Version 8.0 to eliminate a cross-site scripting vulnerability. On Friday morning, Adobe said that its developers have been in touch with Petkov, and are researching the vulnerability. “Once this process is complete, Adobe plans to share further information on the topic via the Adobe Security Bulletins and Advisories page,” a company spokesman said.