MAC Address Randomization was slated as the next big thing for protecting user privacy on the Internet. Now, four scholars from the US Naval Academy say they’ve managed to track 100% of all test smartphones, despite the devices using randomized MAC addresses. The technique worked across all tested manufacturers, and the researchers say this was possible because of a previously unknown flaw in the way wireless chipsets handle low-level control frames. Apple introduced support for MAC address randomization in 2014, with the release of iOS 8, but later broke it last year.
Source: https://www.bleepingcomputer.com/news/security/researchers-break-mac-address-randomization-and-track-100-percent-of-test-devices/