An issue was discovered in the Bluetooth component of the Cypress (formerly owned by…

Summary

An issue was discovered in the Bluetooth component of the Cypress (formerly owned by Broadcom) Wireless IoT codebase. Extended Inquiry Responses (EIRs) are improperly handled, which causes a heap-based buffer overflow during device inquiry. This overflow can be used to overwrite existing functions with arbitrary code. The Reserved for Future Use (RFU) bits are not discarded by eir_handleRx(), and are included in an EIR's length. Therefore, one can exceed the expected 240 bytes, which leads to a heap-based buffer overflow in eir_getReceivedEIR() called by bthci_event_SendInquiryResultEvent(). In order to exploit this bug, an attacker must repeatedly connect to the victim's device in a short amount of time from different source addresses. This will cause the victim's Bluetooth stack to resolve the device names and therefore allocate buffers with attacker-controlled data. Due to the heap corruption, the name will be eventually written to an attacker-controlled location, leading to a write-what-where condition.