Attacks using data-stealing malware and other Trojans accounted for only an estimated 4 percent of Facebook threats. Facebook aggressively monitors for worms and other malware and believes the number of users ever impacted by malware attacks on the site is always well below 1 percent. Last year, a Facebook worm called Ramnit is believed to have compromised 45,000 accounts, ending up stealing passwords of victims. The Ramnit botnet is still being tracked and has been connected to banking malware. Cosoi said he and other threat researchers also have seen botnet owners use Facebook pages and other social networks for command and control purposes.