Cyber criminals induced a massive malware attack on hundreds of porn sites using malicious advertising, affecting millions of visitors. This practice of attacking online users' devices is known as malvertising. The latest attack on popular porn sites attracting millions of visitors on a regular basis was discovered by Malwarebytes, a security firm based in the US.

Several porn sites, including DrTuber, Nuvid, Eroprofile, IcePorn and Xbabe, were affected by the massive malware attack. The malicious ads on these porn sites are hosted by AdXpansion and infect visitors' devices regardless of whether it has been clicked or not.

"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 adverts are served to their visitors.

The latest discovery by MalwareBytes follows the security firm's recent claim that porn sites are safer than we think. A senior security researcher at Malwarebytes Jerome Segura emphasised on the safety of porn sites stating they are a lot safer than several non-porn websites.

"Pornography publishers are about half the publishers we work with. They do take security seriously. Their response times [to attacks] have been significantly better than other publishers'," said Malwarebytes CEO Marcin Kleczynski, according to Tech World.

"Everyone is reliant on a chain of trust which is easily broken by unscrupulous individuals willing to pollute the stream with rogue adverts. The challenge is to find ways of reducing the threat to those at risk from the bad ads," said Boyd.