Threat researchers found another bug in the Apple ecosystem, this one affecting the “Find My” feature that could have leaked historical data about user’s locations.
The Hacker News reported last week that “Cybersecurity researchers on Thursday disclosed two distinct design and implementation flaws in Apple’s crowdsourced Bluetooth location tracking system that can lead to a location correlation attack and unauthorized access to the location history of the past seven days, thereby by deanonymizing users.”
The threat assessors from the Secure Mobile Networking Lab at the Technical University of Darmstadt, Germany, found these two vulnerabilities as part of the Open Wireless Link (OWL) project. The goal of this project is to deconstruct the Apple ecosystem looking for bugs and flaws related to privacy and security.
The Technical Details
The “Find My” feature allows Apple device owners to quickly find or locate a lost iPhone, iPad, iPod Touch, Apple Watch, Mac, or AirPods. The system uses a GPS location system to track each item connected to the app.
A feature built-in to Find My called offline finding added in 2019 uses Bluetooth to broadcast signals from Apple devices to others in their local vicinity.
The Hacker News explained it as “Put differently, offline loading turns every mobile device into a broadcast beacon designed explicitly to shadow its movements by leveraging a crowdsourced location tracking mechanism that’s both end-to-end encrypted and anonymous, so much so that no third-party, including Apple, can decrypt those locations and build a history of every user’s whereabouts.”
“This is achieved via a rotating key scheme, specifically a pair of public-private keys that are generated by each device, which emits the Bluetooth signals by encoding the public key along with it. This key information is subsequently synchronized via iCloud with all other Apple devices linked to the same user (i.e., Apple ID).”
“A nearby iPhone or iPad (with no connection to the original offline device) that picks up this message checks its own location, then encrypts the information using the aforementioned public key before sending it to the cloud along with a hash of the public key.”
“In the final step, Apple sends this encrypted location of the lost device to a second Apple device signed in with the same Apple ID, from where the owner can use the Find My app to decrypt the reports using the corresponding private key and retrieve the last known location, with the companion device uploading the same hash of the public key to find a match in Apple’s servers.”
Researchers said that using public-key encryption (PKE) means Apple cannot identify the user that belongs to the device signature. However, OWL threat assessors claim that because locations will be reported by the same device, Apple could essentially create a “social graph,” identifying users.
Malicious characters and even law enforcement could potentially use this feature to deanonymize users and find their locations and identities.
What is Apple Doing About It?
Apple was notified of the issue on July 2, 2020, when the researchers published their findings. Since then, the problems have been “partially addressed,” according to The Hacker News.
The macOS Catalina vulnerability CVE-2020-9986, potentially allowing hackers to find and download the decryption keys and with it find locations, was patched by Apple in November 2020.
According to The Hacker News, “In May 2019, the researchers disclosed vulnerabilities in Apple’s Wireless Direct Link (AWDL) proprietary mesh networking protocol that permitted attackers to track users, crash devices, and even intercept files transferred between devices via man-in-the-middle (MitM) attacks.”
This particular bug was also identified by Google Project Zero last year.