A scareware attack on Twitter over the weekend is the latest in what has been described as a "worrying new trend" of social networking security attacks.
In the latest attack Twitter users were invited to click on a "best video" link which looked like a link to a YouTube video.
The program embedded in the link also opened a second site, leading to the download of a malware-infected PDF that later installs a rogue security application.
Internet security company Finjan says the growth of attacks like this means companies need to think carefully about allowing staff to access advanced social networking applications from corporate PCs.
It says rogueware affiliate networks are increasingly using search engine optimisation techniques to distribute their rogue anti-virus software for profit.
Traffic volumes to the compromised websites have increased, leading potential buyers to see the software. Finjan said one of the affiliate networks was earning $10,800 a day illegally.