Euprefectorin is a browser hijacker. Oftentimes the hijacker ads may be fake, and they may cause redirects to pages with questionable content. It is not excluded that you might end up landing on some phishing page that tries to get you to fill in some personal details such as credit or debit card numbers just so that the people who’ve created it could scam you and steal money from you. Another possibility is that you get redirected to a page that shows you a fake warning about a threat in your computer that, and tells you to purchase some obscure security software that would supposedly fix the problem (which doesn’t even exist). Of course, not all ads related to a browser hijacker such as Euprefectorin or Lookaside.fbsbx.com are like that, but it is possible that some of them may indeed be unreliable and potentially unsafe.