Recent analysis from the FBI and other government agencies demonstrates that malicious actors are targeting travelers abroad through pop-up windows while establishing an Internet connection in their hotel rooms.
When computer owners are in a hotel, and use the hotel’s Wi-Fi, computer owners are generally presented a web page or dialog to log into the service. Apparently, some smart cyber-criminals have found ways to hack these web pages.
This should also extend to any public Wi-Fi network. It is also recommended to download software updates directly from vendor's web site.
Currently, Firefox checks itself every now and then for the sack of chasing the latest version. This behaviour can cost travellers expensive Wi-Fi quota(*) and as FBI suggested this forceful setting may resulted users' computer being infected.
(*) Most Wi-Fi services in hotel/motel are charged by quota, and generally pretty expensive.
UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:12.0) Gecko/20100101 Firefox/12.0 AlexaToolbar/alxf-2.15