It seems that theory has been put into practice in the US, with hackers creating a series of rogue WiFi access points in airports, for travellers to log on to for free.
The only problem is - all the data entered by the traveller gets seen by the hackers on their laptop.
The scam was reported by Computerworld magazine last week, which has prompted the magazine to warn travellers to beware of airport wireless hot spots.
And for the icing on the cake , Computerworld says that travellers can end up with their IDs and passwords stolen, as well as see their laptop riddled with advanced spyware and trojans.
So far, IT research firm Authentium has found rogue WiFi access points in Atlanta, New York, Florida's West Palm Beach and Chicago airport, whilst Internet users have reported others in Los Angeles.
Nasty stuff - how long before the technique gets copied here in the UK? Not long, I shouldn't wonder...