Security firm McAfee reports exploits of Adobe's PDF format skyrocketed last year, and continue to climb this year. Two to three years ago only 2 percent of all malware focused on Adobe Reader, but this year the number has jumped to 28 percent. One of the reasons for this is because it's increasingly difficult to find exploits in Windows or Internet browsers, which makes other widely used software such as Adobe Reader and Flash a more popular target.
According to Toralv Dirro, a security strategist with McAfee Labs, the percentage of exploitative malware targeting PDF vulnerabilities has skyrocketed. In 2007 and 2008, only 2% of all malware that included a vulnerability exploit leveraged an Adobe Reader or Acrobat bug. The number jumped to 17% in 2009, and to 28% during the first quarter of 2010.
"In the last three years, attackers have found PDF vulnerabilities more and more useful, for a couple of reasons," Dirro said. "First of all, it's increasingly difficult for them to find new vulnerabilities with the operating system and within browsers that they can exploit across the different versions of Windows. And second, Reader is one of the most widely deployed applications that allows files to be accessed or opened within the browser."
Other factors for the jump in PDF exploits, argued Dirro, range from user belief that PDFs are safe to open, or at least safer to open than Microsoft Office documents, to the age of Adobe's code. "Quite a lot of PDF code was written years ago, and attackers are finding new security problems that no one thought of then," Dirro said. "That makes it difficult for Adobe to clean it up."