Porn users might be starting to miss the safety provided by seedy movie theaters and VHS rental stores. Hundreds of major adult video providers have been targeted with advertising that includes malicious software, with a new campaign aimed at visitors who log on to IcePorn, DrTuber, Xbabe and others.

Those sites, along with Nuvid, Eroprofile, and hundreds of others that regularly attract millions of visitors, are the latest victims of a malvertising crime spree that began no later than Nov. 21.

Attackers exploit a security flaw found in software used by AdXpansion, an adult advertising network, to launch a pop-up that automatically tries to infect a user without even being clicked, according to research unveiled Wednesday by the cybersecurity company Malwarebytes. This comes after similar attacks assaulted other popular porn ad networks, including ones that run on Pornhub, RedTube, Xvideos and Xhamster.

“It isn't so much that pornography sites are targeted ... as the adult advertising networks,” Chris Boyd, an analyst at Malwarebytes, told IBTimes UK. “The end result of infected PCs is still the same, but as with most forms of malvertising, the websites themselves tend to have little control over which advertisements are served to their visitors. ... Everyone is reliant on a chain of trust which is easily broken by unscrupulous individuals willing to pollute the stream with rogue adverts.”

Infected computers were compromised with a number of different malware strains, including ransomware, which encrypts users' data and threatens to delete it unless payment demands are met.