AirDrop allows Mac and iPhone users to wirelessly transfer files between devices. The feature is leaking user emails and phone numbers, and there’s not much to do to stop it. AirDrop uses Wi-Fi and Bluetooth Low Energy to establish direct connections with nearby devices. Hackers do this by performing a “brute-force attack,” which throws huge numbers of guesses and waits for the one that generates the sought-after hash. Attack could be useful when attacker is someone whose phone number or email address is well-known to many people.”]