CVE-2018-19860 in macOS
Summary
by MITRE
Broadcom firmware before summer 2014 on Nexus 5 BCM4335C0 2012-12-11, Raspberry Pi 3 BCM43438A1 2014-06-02, and unspecifed other devices does not properly restrict LMP commnds and executes certain memory contents upon receiving an LMP command, as demonstrated by executing an HCI command.
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Analysis
by VulDB Data Team • 11/06/2023
This vulnerability resides in the Broadcom wireless firmware implementations found on various mobile and embedded devices including the Nexus 5 and Raspberry Pi 3 models. The flaw specifically affects firmware versions released before the summer of 2014, with particular attention to the BCM4335C0 chip used in Nexus 5 devices and BCM43438A1 chip in Raspberry Pi 3 models. The vulnerability stems from inadequate input validation and command restriction mechanisms within the Link Manager Protocol (LMP) implementation, which governs the communication between Bluetooth devices and their host systems. This represents a critical security gap that allows malicious actors to exploit the wireless stack through carefully crafted LMP commands that should be properly restricted or validated.
The technical execution of this vulnerability occurs when the firmware receives specific LMP commands that trigger memory execution without proper validation of the command parameters. This behavior constitutes a classic buffer overflow or memory corruption vulnerability where legitimate system functions become accessible through malicious command injection. The exploitation process involves sending specially crafted HCI (Host Controller Interface) commands that bypass normal access controls, allowing arbitrary code execution within the firmware context. This type of vulnerability aligns with CWE-787: "Out-of-bounds Write" and CWE-119: "Improper Restriction of Operations within the Bounds of a Memory Buffer" as it involves executing memory contents through improper command handling. The vulnerability demonstrates poor input sanitization and inadequate privilege separation between user-level commands and system-level memory operations.
The operational impact of this vulnerability extends beyond simple code execution to potentially compromise entire device systems. Attackers could leverage this flaw to gain unauthorized access to device functionality, execute arbitrary code, and potentially establish persistent backdoors within the wireless subsystem. The affected devices operate in environments where wireless connectivity is critical, making this vulnerability particularly dangerous for mobile devices and embedded systems. The vulnerability affects devices that rely on Broadcom's wireless chipsets for Bluetooth and Wi-Fi connectivity, creating a widespread impact across multiple device categories and manufacturers. This type of attack vector is categorized under ATT&CK technique T1059.007: "Command and Scripting Interpreter: PowerShell" in the context of firmware-level command execution, though the actual execution occurs at the hardware level rather than through traditional software interfaces.
Mitigation strategies for this vulnerability require immediate firmware updates from device manufacturers, as the flaw exists at the hardware abstraction layer level. Users should ensure their devices receive the latest firmware patches that address the LMP command validation issues and implement proper memory execution restrictions. Network administrators should monitor for unusual wireless activity patterns that might indicate exploitation attempts, while device manufacturers need to implement more robust input validation mechanisms in their wireless stack implementations. The vulnerability highlights the importance of secure firmware development practices and proper code review processes for embedded systems, particularly those handling sensitive communications protocols. Organizations should also consider network segmentation and monitoring to detect potential exploitation attempts, as the vulnerability could enable attackers to establish persistent access to wireless-enabled devices. Given the nature of the flaw, complete remediation requires firmware-level fixes rather than software patches alone, making vendor cooperation and prompt update deployment critical for device security.