Evil twins (see Wikipedia) or rogue access points are WLANs that pretend to be a WLAN you know, e.g. the WLAN of your apartment or the eduroam WLAN at the university. If your mobile device tries to log in automatically or if you log in to this WLAN yourself (Evil Twin), your access data can be stolen from the supposedly real WLAN.

The best protection against such attacks is to deactivate WLAN in public areas for the time being. Only if I am in the vicinity where I can expect the respective WLAN, one should connect to the respective WLAN.

Regarding eduroam, using eduroam CAT is a good protection. Install eduroam CAT on all your devices instead of setting up the eduroam WLAN manually.

On latest smartphones, where CAT is not available anymore, please use geteduroam.