CVE-2017-6957 in HardMAC SoC
Summary
by MITRE
Stack-based buffer overflow in the firmware in Broadcom Wi-Fi HardMAC SoC chips, when the firmware supports CCKM Fast and Secure Roaming and the feature is enabled in RAM, allows remote attackers to execute arbitrary code via a crafted reassociation response frame with a Cisco IE (156).
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Analysis
by VulDB Data Team • 11/22/2022
The vulnerability CVE-2017-6957 represents a critical stack-based buffer overflow affecting Broadcom Wi-Fi HardMAC SoC chips that implement firmware support for CCKM Fast and Secure Roaming functionality. This flaw exists within the embedded firmware components of wireless networking hardware, specifically impacting devices that utilize Broadcom's wireless chipsets in enterprise and consumer environments. The vulnerability is particularly concerning because it enables remote code execution through a crafted reassociation response frame containing a Cisco IE (156) element, making it exploitable over the air without requiring physical access or authentication.
The technical implementation of this vulnerability stems from improper bounds checking within the firmware's handling of wireless management frames. When the CCKM Fast and Secure Roaming feature is enabled in RAM, the firmware processes reassociation response frames without adequate validation of the Cisco IE (156) field length. This allows attackers to craft malicious frames that exceed the allocated stack buffer space, causing a buffer overflow condition that can be leveraged to overwrite critical memory locations including return addresses and execution pointers. The vulnerability is classified as a stack-based buffer overflow under CWE-121, which directly maps to the ATT&CK technique T1059.007 for execution through command and scripting interpreter, as successful exploitation can lead to arbitrary code execution.
The operational impact of this vulnerability extends across numerous wireless networking environments where Broadcom chipsets are deployed, including enterprise networks, public Wi-Fi hotspots, and consumer devices such as laptops, smartphones, and IoT appliances. Attackers can exploit this vulnerability remotely by positioning themselves within wireless range of affected access points, making it particularly dangerous in densely populated areas such as office buildings, airports, or public venues. The ability to execute arbitrary code on affected devices could lead to complete system compromise, enabling attackers to establish persistent backdoors, exfiltrate sensitive data, or use compromised devices as launching points for further network attacks. Organizations with extensive wireless infrastructure deployments face significant risk exposure, as a single vulnerable access point could potentially compromise an entire wireless domain.
Mitigation strategies for CVE-2017-6957 require immediate attention from network administrators and security teams. The primary recommended approach involves firmware updates from Broadcom or device vendors that address the buffer overflow condition through proper bounds checking and input validation. Network segmentation and monitoring solutions should be deployed to detect anomalous wireless traffic patterns that may indicate exploitation attempts. Additionally, disabling the CCKM Fast and Secure Roaming feature when not required provides a temporary workaround while longer-term patches are deployed. Security controls should include wireless intrusion detection systems that can identify and alert on malformed reassociation response frames containing Cisco IE (156) elements. Organizations should also implement network access control measures to limit wireless device capabilities and reduce the attack surface available to potential exploiters. Regular vulnerability assessments and penetration testing of wireless infrastructure are essential to identify and remediate similar vulnerabilities before they can be exploited in real-world scenarios.