The largest such attack known to date, Cisco researchers say. Victims are emailed an alert that contains a link with a fictitious social media contact request. As of Monday, these messages accounted for as much as 24 percent of all spam sent within a 15-minute interval. This is not the first time criminals have subverted brands associated with online social media, Cisco noted. “The LinkedIn attacks are just a new medium for the same attackers,” says Matt Jonkman, founder of Emerging Threats.”]