How Captive Portals Interfere With Wireless Security and Privacy

Captive portals – intermediary screens that shown you the network’s Terms of Service and prompt you to click an “I agree” button – are to blame for a number of security issues, especially when it comes to HTTPS websites. HTTPS is meant to prevent traffic interception, alteration, and impersonation by a third party. But captive portals work by doing exactly that: they intercept and alter the connection between the user and the site they are trying to visit.

Source: How Captive Portals Interfere With Wireless Security and Privacy | Electronic Frontier Foundation