ZDNet: According to a new report, malicious PDFs accounted for 56 percent of exploits in the first quarter of last year, but a full 80 percent of all exploits by the fourth quarter. As PDF exploits rose, Flash exploits dropped from 40 percent in the first quarter of 2009 to 18 percent in the fourth quarter.
The report's authors blame the growth in malicious PDF files on vulnerabilities in Adobe software and widespread use of the file format. However, ZDNet also points out "the increasing use of malicious PDFs can also be interpreted as the direct result of the millions of users using outdated and exploitable Adobe products." They recommend that users double-check to make sure they are using the latest versions of Adobe software.