More malware targeting popular porn sites emerged over the weekend, with Pornhub and YouPorn being the latest affected.
Spotted by security firm Malwarebytes, hackers inserted a rogue piece of legitimate-seeming code into the ExoClick ad network used by the websites, with the resulting adware appearing as an ad banner.
The malicious code, known as cookiecheck.js, was quickly removed by the ad network and by the porn sites' publisher, MindGeek, thereby protecting their 800 million monthly visitors.
But had the code not been spotted quickly, it would have redirected victims to an Angler Exploit Kit that hackers could have used to infect their victims' computers with programs like ransomware.
Other porn sites have been served similar malware by hackers in the last fortnight, with xHamster targeted by an SSL malvertising campaign that was first seen on Yahoo.com and MSN.com.
Malwarebytes called the recent prevalance of porn site attacks "strange", adding: "During the past several months, high profile malvertising attacks against top adult sites have been sparse.
"This makes what we have seen during the past couple of weeks very unusual but also impactful given the sheer volume of traffic these sites receive."
MindGeek said in a statement: "We were alerted to the presence of a malicious advertisement appearing on a select few of Pornhub's web properties. It was quickly determined that the malware originated from a third party advertising partner, and we responded immediately to disable all advertisements associated with this third party, and continue to actively investigate this incident."
