What’s Really Happening With iOS 8 MAC Address Randomization
Initially it looked as if MAC randomization didn’t work at all, which was confusing because Apple has made a point to publicize this feature.
After a lot of digging and a lot of late nights monitoring Wireshark captures, it looks like Apple has shipped this feature as advertised, but not quite as expected. In the WWDC session on user privacy, the slide said “The MAC address used for Wi-Fi scans may not always be the device’s real (universal) address”. They didn’t say it would never be a device’s real MAC, only that it may not always be.
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Unfortunately, the requirement of the phone being asleep makes this feature nearly useless, albeit within the description of what Apple advertised at WWDC. In order to get random MACs to be used I had to turn off notifications for multiple apps, turn off push email, and stay up late at night when there was a greater chance of my phone getting to sleep, uninterrupted, for more than a minute or two. Even under these circumstances, I would only encounter one or two rounds of probe beacons (which seem go to out every couple of minutes) with a random MAC before seeing my phone blast a bunch of probes with my real MAC.
Previously: iOS 8 MAC Address Randomization.
