A first-of-its-kind security analysis of the iOS Find My function has identified a new attack surface that makes it possible to tamper with firmware and load malware onto a Bluetooth chip that is executed while the iPhone is “turned off”.
The mechanism takes advantage of the fact that wireless chips related to Bluetooth and NFC (NFC) and very broadband (UWB) Continue to work while iOS is turned off when entering Low Power Reserve Mode (LPM).
While this is done to enable features like find and facilitate Express Card Transactionsall three wireless chips have direct access to the secure component, academics from the Secure Mobile Networks Laboratory (SEEMOOat the Technical University of Darmstadt She said In an article entitled “Evil never sleeps.”
“The Bluetooth and UWB chips are connected to the secure element (SE) of the NFC chip, which stores secrets that should be available in the LPM,” the researchers said.
“Because LPM support is implemented in hardware, it cannot be removed by changing software components. As a result, on modern iPhones, wireless chipsets can no longer be trusted to turn off after shutdown. This constitutes a new threat model.”
The results are due to be Foot At the ACM Conference on Security and Privacy in Wireless and Mobile Networks (WiSec 2022) this week.
Newly introduced last year with iOS 15, LPM features make it possible to track lost devices using the Find My network even when the battery is dead or turned off. Existing devices with ultra broadband support included iPhone 11, iPhone 12 and iPhone 13.
A message appears when iPhones are turned off read like this: “iPhone remains findable after a power outage. Find My helps you locate this iPhone when it is lost or stolen, even when it’s in power reserve mode or when it’s turned off.”
The researchers called the current LPM app “dark,” and not only did they occasionally notice failures when initializing Find My Ads during a power outage, effectively contradicting the above message, but also found that the Bluetooth firmware was neither signed nor encrypted.
By taking advantage of this vulnerability, an adversary with privileged access can create malware that can be executed on the iPhone Bluetooth chip even when it is turned off.
However, for such a firmware hack to occur, an attacker must be able to communicate with the firmware via the operating system, modify the firmware image, or get code execution on an over-the-air LPM-enabled chip by exploiting flaws such as BrakTooth.
In other words, the idea is to modify the LPM application thread to include malware, such as one that can alert the malicious actor to the victim. Find my bluetooth broadcastsenabling the threat actor to keep remote tabs on the target.
The SEEMOO researchers noted that “instead of changing existing functionality, they can also add completely new features,” adding that they responsibly disclosed all the issues to Apple, but the tech giant “has no feedback.”
With LPM-related features taking a more discreet approach to implementing their intended use cases, SEEMOO called on Apple to include a hardware-based battery disconnect switch so as to mitigate any control Fears That may arise from attacks at the firmware level.
“Because LPM support relies on iPhone hardware, it cannot be removed with system updates,” the researchers said. “Thus, it has a long-term impact on the overall iOS security model.”
“LPM’s feature design appears to be driven mostly by functionality, without taking into account threats outside of its intended applications. Find My after power off turns iPhones into tracking devices by design, and implementation within the Bluetooth firmware is not secured against tampering.”