CVE-2016-7957 in Wireshark
Summary
by MITRE
In Wireshark 2.2.0, the Bluetooth L2CAP dissector could crash, triggered by packet injection or a malformed capture file. This was addressed in epan/dissectors/packet-btl2cap.c by avoiding use of a seven-byte memcmp for potentially shorter strings.
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Analysis
by VulDB Data Team • 11/28/2022
The vulnerability identified as CVE-2016-7957 represents a critical buffer over-read condition within Wireshark's Bluetooth L2CAP dissector component. This flaw existed in Wireshark version 2.2.0 and could be exploited through two primary vectors: packet injection attacks or by processing malformed capture files that contained malformed Bluetooth L2CAP protocol data. The technical root cause stems from improper memory validation during protocol packet parsing, specifically involving a seven-byte memcmp operation that was being executed against potentially shorter string buffers. This memory comparison function lacked proper bounds checking, creating an opportunity for attackers to trigger a denial of service condition through carefully crafted malicious packets or capture files. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and represents a classic example of a buffer overflow condition that can lead to application crashes. When the dissector encountered malformed Bluetooth L2CAP packets, the insufficient bounds checking in packet-btl2cap.c caused the application to attempt memory access beyond the allocated buffer boundaries, resulting in unpredictable behavior and potential system instability.
The operational impact of this vulnerability extends beyond simple application crashes, as it could be leveraged by malicious actors to disrupt network monitoring operations and potentially gain unauthorized access to systems relying on Wireshark for network protocol analysis. Network security professionals and system administrators who depend on Wireshark for traffic analysis and troubleshooting could face significant operational disruptions when encountering malicious or malformed Bluetooth traffic. The vulnerability particularly affects environments where wireless network monitoring is critical, including enterprise networks, security operations centers, and wireless penetration testing environments. Attackers could exploit this weakness by injecting specially crafted Bluetooth L2CAP packets into network traffic or by creating malicious capture files that, when opened in Wireshark, would trigger the memory access violation. This makes the vulnerability particularly dangerous in environments where automated network monitoring systems process untrusted network traffic without proper sanitization.
The fix implemented by the Wireshark development team addressed the core technical flaw by modifying the epan/dissectors/packet-btl2cap.c file to eliminate the problematic seven-byte memcmp operation. This remediation ensures that memory comparison operations are performed only against properly validated buffer sizes, preventing the buffer over-read condition that previously led to application crashes. The solution follows established best practices for secure coding and aligns with ATT&CK technique T1059.007 for execution through command injection, though in this case the attack vector is more accurately characterized as a memory corruption vulnerability. Organizations should prioritize patching affected systems to prevent exploitation, as the vulnerability could be used in combination with other attack vectors to create more sophisticated network intrusion scenarios. The fix demonstrates the importance of proper bounds checking in protocol dissector implementations and highlights the critical need for robust input validation in network analysis tools that process potentially malicious network traffic from multiple sources.