Cyber criminals are getting a head start at taking advantage of the upcoming London Olympics. Researchers at security firm F-Secure said this week they have spotted a malicious PDF making the rounds that opens a legitimate copy of the Games' schedule, but in the background it tries to connect to a malicious website. F-Secure security adviser Sean Sullivan said in a blog post that the exploit takes advantage of an Adobe Reader and Acrobat vulnerability that was patched in 2010. He recommended users be wary of Olympics-themed emails containing attachments or links. Just last week, U.S. cyber security officials warned that the event, which kicks off in late July, could be a haven for cyber criminal activity.