TI’s BLE stack caches and reuses the LTK’s property for a bonded mobile. A LTK can be an unauthenticated-and-no-MITM-protection key created by Just Works or an authenticated-and-MITM-protection key created by Passkey Entry, Numeric Comparison or OOB. Assume that a victim mobile uses secure pairing to pair with a victim BLE device based on TI chips and generate an authenticated-and-MITM-protection LTK. If a fake mobile with the victim mobile’s MAC address uses Just Works and pairs with the victim device, the generated LTK still has the property of authenticated-and-MITM-protection. Therefore, the fake mobile can access attributes with the authenticated read/write permission.
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
| Link | Tags |
|---|---|
| http://software-dl.ti.com/simplelink/esd/simplelink_cc13x2_26x2_sdk/3.20.00.68/exports/changelog.html | vendor advisory |
| https://www.usenix.org/system/files/sec20-zhang-yue.pdf | third party advisory exploit |