As browser vendors improve their security efforts, cybercriminal tactics evolve and adapt to bypass those safeguards. An example of this cat-and-mouse game is the increased use of Hypertext Transfer Protocol Secure (HTTPS) in phishing attacks. According to Netcraft, researchers observed a sharp hike — from roughly 5 percent to 15 percent — in the number of phishing sites using HTTPS to communicate since January 2017.

Phishing Sites Get Even Phishier

The timing of this surge coincides with the introduction of a new security feature in Chrome v56 and Firefox v51 that warns users when they enter login credentials on a page that does not support HTTPS. This alert mechanism was designed to protect against man-in-the-middle attacks. Microsoft’s Edge and Internet Explorer browsers do not yet exhibit this behavior.

Netcraft reported that these new alerts may have paradoxically boosted the efficiency of phishing sites. Meanwhile, SecurityWeek noted that the browsers’ security enhancements prompted cybercriminals to step up their game and devise even trickier schemes.

Fraudsters Step Up Their Game

Phishing fraudsters use services such as Let’s Encrypt to access valid digital certificates. When a valid certificate is combined with HTTPS, the phishing site seems more legitimate to a potential victim, and the browser will not flag the site for missing elements.

Additionally, the emergence of the new browser alerts have caused legitimate websites to adopt HTTPS at an increasing rate to avoid triggering the alerts. This phenomenon also likely contributed to the rise in HTTPS use among cybercriminals; if a legitimate site has also been hijacked by a malicious actor, the protocol changes made in those sites will also be reflected in the phishing segment.

Users must always be alert when they are entering credentials on any site and pay close attention to the destination URL for any site requesting them.