CVE-2016-9797 in BlueZ
Summary
by MITRE
In BlueZ 5.42, a buffer over-read was observed in "l2cap_dump" function in "tools/parser/l2cap.c" source file. This issue can be triggered by processing a corrupted dump file and will result in hcidump crash.
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Analysis
by VulDB Data Team • 06/15/2019
The vulnerability identified as CVE-2016-9797 represents a critical buffer over-read flaw within the BlueZ Bluetooth protocol stack version 5.42. This issue resides in the l2cap_dump function located in the tools/parser/l2cap.c source file, which serves as a crucial component for parsing and analyzing Bluetooth Low Energy and classic Bluetooth L2CAP (Logical Link Control and Adaptation Protocol) packets. The vulnerability demonstrates a classic software security weakness that can lead to system instability and potential exploitation by malicious actors. The flaw specifically manifests when the system processes corrupted or malformed dump files generated by hcidump, which is a tool used for capturing and displaying Bluetooth HCI (Host Controller Interface) packets. This type of vulnerability falls under the CWE-125 weakness category, which describes out-of-bounds read conditions that occur when a program reads data past the end of a valid buffer, potentially exposing sensitive memory contents or causing program termination.
The operational impact of this vulnerability extends beyond simple application crashes, as it represents a potential denial-of-service vector that could be exploited in environments where Bluetooth connectivity is critical. When a malicious actor crafts a specially formatted dump file that triggers the buffer over-read condition, the hcidump utility will crash and terminate unexpectedly, disrupting Bluetooth monitoring and debugging operations. This behavior can be particularly problematic in security auditing scenarios where continuous monitoring of Bluetooth traffic is required, or in production environments where Bluetooth services are integral to device functionality. The vulnerability's exploitation pathway demonstrates how seemingly benign tools can become attack vectors when they fail to properly validate input data, creating opportunities for attackers to disrupt services or potentially escalate privileges. From an ATT&CK framework perspective, this vulnerability maps to the T1059.007 technique related to command and script interpreter execution, as the crash can be induced through command-line interactions with the affected tool, and potentially to T1499.004 for network denial of service through resource exhaustion.
Mitigation strategies for CVE-2016-9797 should focus on both immediate remediation and long-term architectural improvements to prevent similar issues in the Bluetooth stack. The most direct solution involves upgrading to BlueZ versions that contain patches for this vulnerability, as the maintainers have addressed the buffer over-read condition through proper bounds checking and input validation. Organizations should also implement defensive programming practices such as validating all input data before processing, implementing proper buffer size checks, and employing memory safety techniques like stack canaries or address sanitization tools during development. Additionally, security monitoring should include detection of abnormal hcidump behavior or unexpected crashes, as these could indicate exploitation attempts. The vulnerability highlights the importance of robust input validation in network protocol implementations and serves as a reminder that tools designed for debugging and monitoring should not become security liabilities themselves. Implementing proper error handling and graceful degradation mechanisms would have prevented the crash scenario and maintained system stability even when encountering malformed input data. Organizations should also consider implementing network segmentation and access controls around Bluetooth interfaces to limit potential attack surfaces, particularly in environments where Bluetooth monitoring tools are actively used for security purposes.