Neil Jones, director of cybersecurity evangelism at Egnyte, argued that the data collected by the apps could also be a treasure trove for would-be cyber-criminals. “If you plan to travel to the event, I would strongly recommend the purchase of a burner phone, if the privacy-limiting capabilities cannot be disabled,” he added. “If prompted, allow only the minimum permissions for the application to function on your device. Strongly consider limiting other users’ access to view your geographical location. Don’t allow the application to make calls on your behalf or alter your device’s data. Consider deleting event-related applications when the events have concluded.”
https://www.infosecurity-magazine.com/news/euro-authorities-world-cup-fans/

