CVE-2017-11121 in tvOS
Summary
by MITRE
On Broadcom BCM4355C0 Wi-Fi chips 9.44.78.27.0.1.56 and other chips, properly crafted malicious over-the-air Fast Transition frames can potentially trigger internal Wi-Fi firmware heap and/or stack overflows, leading to denial of service or other effects, aka B-V2017061205.
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Analysis
by VulDB Data Team • 01/20/2021
The vulnerability CVE-2017-11121 targets Broadcom BCM4355C0 Wi-Fi chips and related hardware implementations, specifically addressing a critical heap and stack overflow condition within the wireless firmware. This issue manifests through properly crafted Fast Transition frames transmitted over the air, which are part of the IEEE 802.11k/v standard designed to facilitate seamless roaming between access points. The vulnerability represents a sophisticated attack vector that leverages the legitimate Fast Transition functionality to execute malicious code within the chip's firmware environment.
The technical flaw resides in the improper handling of Fast Transition frames within the Broadcom Wi-Fi chip's firmware implementation, creating conditions where maliciously constructed frames can cause buffer overflows in both heap and stack memory regions. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow scenarios. The chip's firmware fails to properly validate frame lengths and content during the Fast Transition processing phase, allowing attackers to inject malformed data that exceeds allocated buffer boundaries.
From an operational perspective, this vulnerability creates significant risks for wireless network security and availability. The attack can result in complete denial of service conditions where affected devices become unresponsive or require manual rebooting to recover functionality. In some cases, the overflow conditions may potentially allow for more severe consequences including arbitrary code execution within the firmware context, though the primary impact remains denial of service. The vulnerability affects numerous devices including laptops, smartphones, and IoT devices that utilize Broadcom Wi-Fi chipsets, creating widespread potential impact across enterprise and consumer networks.
The attack requires minimal privileges and can be executed remotely through wireless transmission, making it particularly dangerous for enterprise environments where wireless infrastructure is extensively deployed. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and control through wireless protocols and T1499.004 for network disruption. The attack surface extends beyond individual devices to potentially compromise entire wireless networks where multiple affected devices exist. Organizations should prioritize firmware updates from device manufacturers and implement network monitoring to detect anomalous Fast Transition frame traffic patterns that may indicate exploitation attempts.
Mitigation strategies should include immediate firmware updates from device vendors, network segmentation to limit exposure, and implementation of wireless intrusion detection systems that can identify malformed Fast Transition frames. Network administrators should also consider disabling Fast Transition functionality if not required for network operations, though this may impact wireless roaming performance. Regular vulnerability assessments of wireless infrastructure and monitoring for unusual device behavior remain essential defensive measures against this and similar wireless firmware vulnerabilities.