BlueZ AVRCP Packet Length Validation Flaw Leads to DoS

Executive Summary

This vulnerability is an out-of-bounds memory read flaw in BlueZ's Audio/Video Remote Control Profile (AVRCP) implementation. It occurs when a malicious Bluetooth device sends invalid packet length fields in GetFolderItems responses, affecting the parse_media_element() and parse_media_folder() functions. This can crash the bluetoothd daemon, causing a Denial of Service (DoS), and may expose sensitive heap memory contents.

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Detection Guidance

This vulnerability requires a malicious Bluetooth device within range to exploit it. Detection involves monitoring for unexpected Bluetooth device behavior or crashes of the bluetoothd daemon. Check system logs for bluetoothd crashes or unusual memory access errors. Use commands like 'journalctl -u bluetooth' to review Bluetooth service logs for errors or warnings.

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Impact Analysis

The impact includes a Denial of Service (DoS) where the bluetoothd daemon crashes, disrupting Bluetooth functionality. It may also expose limited heap memory contents, potentially leaking sensitive information. Exploitation requires a malicious device within range and user interaction to pair with it.

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Compliance Impact

This vulnerability may impact compliance with GDPR and HIPAA by potentially exposing sensitive heap memory contents through an out-of-bounds memory read. GDPR requires protection of personal data, and HIPAA mandates safeguarding protected health information. A memory disclosure could lead to unauthorized access to sensitive data, violating these regulations if exploited.

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Mitigation Strategies

Disable the AVRCP Bluetooth profile if unused via system settings or configuration files. Restrict Bluetooth pairing to trusted devices only. Consider disabling the Bluetooth subsystem entirely if not required. Apply any available patches or updates from your BlueZ distribution vendor.

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