It’s always porn’s fault.

Yet another cybersecurity firm has studied mobile internet users and their habits and determined porn is a primary vector for malware and malvertising, as well as a major source of data leakage.

“Almost a quarter of malware on mobile devices comes from porn websites,” researcher Liarna La Porta wrote on the Wandera blog. “Watching mobile porn on your smartphone is a much higher risk than watching it on your PC. Smartphone operating systems, especially Android, are not as secure as desktops; there are many vulnerabilities that can be easily exploited by hackers.”

La Porta indicated Wandera’s study, documented in the company’s “2017 Mobile Leak Report” (free), also found adult websites leave users’ personally identifiable information, or PII, exposed. She mentioned the Ashley Madison, AdultFriendFinder and Brazzer’s database breaches, saying “the naughtiest apps are also the leakiest.”

“Pornography and other adult content categories are notorious for lax handling of PII,” she wrote. “In fact, 40 out of the top 50 adult sites were exposed at the time of research [in 2016].”

(The research took place well before the recent database breach at credit-reporting agency Equifax, which reportedly exposed the PII of 143 million Americans. The debacle proved porn isn’t the only leaky industry online — or the most dangerous when it does leak.)

Wandera examined 100,000 mobile devices U.S. and U.K. companies provided to their employees. During the research period, 34 of every 10,000 devices accessed pornography or other “adult materials” (gambling, violence, illegal drugs, hate speech, etc.) on a daily basis, according to the report. Analysis indicated Fridays were the most popular day for users to access “inappropriate material,” followed by Thursdays. Access was lowest on Mondays.

Typically, the employees didn’t use their phones for surfing porn during the workday; “dark side” viewing began in earnest about 8 p.m. and peaked at 2-3 a.m., the report noted.