I'm looking into security holes in my daily life, and I ran across an article that says that most devices broadcast their MAC address continuously. I'm wondering if that applies to iPhones (and other iDevices) as well. I would expect them to use active scanning when Ask to Join Networks is on, or if you are actually in the Wi-Fi Settings (though I don't know that that is the case), but what about normally? Is my iPhone broadcasting its identity everywhere it goes as long as the Wi-Fi is on?

  • How would one's MAC address be used as a security hole? – l008com Mar 25 '18 at 9:44
  • Because it's unique to your device, so that you can be tracked from place to place. As the article I linked says, "basic analysis of this kind of data from a shopping centre can tell me what shops you visit or what areas you like to spend time in. I can tell how long you spend in my building – and where you enter and leave. I can tell how fast you walked from one end to the other. I can tell if you visited the bathroom. I can likely tell if you drove to my building – or took the bus. For me (or any scary three letter organisations), this information is pure gold." – Calion Mar 29 '18 at 13:47

Since iOS8 the MAC is randomised while scanning for wi-fi networks. I believe that has since been adopted by most devices.

The REAL MAC is only used after connection to a network.

  • Interesting. Do you have a reference for this? – Calion Mar 22 '18 at 15:01
  • 1
    See the WiFi section of Apple's iOS Security Guide (PDF). It says iOS 11 "uses randomized Media Access Control (MAC) address when conducting Wi-Fi scans ..." – creidhne Jul 18 '18 at 5:24

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