CVE-2018-14854 in Galaxy S6
Summary
by MITRE
Buffer overflow in dhd_bus_flow_ring_delete_response in drivers/net/wireless/bcmdhd4358/dhd_pcie.c in the bcmdhd4358 Wi-Fi driver on the Samsung Galaxy S6 SM-G920F G920FXXU5EQH7 allow an attacker (who has obtained code execution on the Wi-Fi chip) to cause the device driver to perform invalid memory accesses. The Samsung ID is SVE-2018-11785.
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Analysis
by VulDB Data Team • 04/21/2020
The vulnerability CVE-2018-14854 represents a critical buffer overflow condition within the bcmdhd4358 Wi-Fi driver component of Samsung's Galaxy S6 SM-G920F device. This flaw exists in the dhd_bus_flow_ring_delete_response function located in the drivers/net/wireless/bcmdhd4358/dhd_pcie.c file, which forms part of the Linux kernel's wireless networking subsystem. The vulnerability specifically affects the PCIe-based Wi-Fi chip implementation and creates a pathway for malicious code execution that can lead to arbitrary code execution within the device's kernel space. The Samsung internal tracking identifier SVE-2018-11785 indicates this was recognized as a significant security concern by the vendor. This type of vulnerability falls under the CWE-121 CWE category for stack-based buffer overflow, though the specific implementation suggests heap-based memory corruption due to the PCIe bus interaction patterns. The vulnerability demonstrates a classic memory safety issue where insufficient bounds checking allows an attacker to overwrite adjacent memory locations.
The technical flaw manifests when the Wi-Fi driver processes flow ring delete responses from the wireless chip, which are part of the PCIe communication protocol used to manage data transmission queues. During normal operation, the driver maintains flow rings to track pending data transfers between the host system and the Wi-Fi chip. When processing a delete response, the driver fails to properly validate input parameters or enforce buffer boundaries, allowing an attacker who has already achieved code execution on the Wi-Fi chip to craft malicious responses that exceed allocated buffer space. This overflow can overwrite critical driver data structures, function pointers, or return addresses, potentially leading to complete system compromise. The attack vector requires an attacker to first gain execution privileges on the Wi-Fi chip itself, which represents a sophisticated attack scenario involving hardware-level exploitation. However, once achieved, the vulnerability creates a privilege escalation path from the Wi-Fi chip's execution context to the full kernel execution context, making it particularly dangerous in mobile device environments where kernel-level access provides complete system control.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables a wide range of malicious activities through the ATT&CK framework's privilege escalation and persistence tactics. An attacker could leverage this vulnerability to execute arbitrary code with kernel-level privileges, potentially installing rootkits, modifying system files, or creating persistent backdoors within the device's operating system. The vulnerability affects Samsung Galaxy S6 devices specifically, which were widely deployed and represent a significant user base that would benefit from immediate remediation. The PCIe-based nature of the vulnerability means that the attack could potentially be initiated through network-based exploitation if the attacker can influence the data transmitted between the device and wireless access points. This makes the vulnerability particularly concerning for enterprise environments where these devices might be used in sensitive corporate networks. The memory corruption could also lead to system crashes or denial of service conditions, though the primary concern remains the privilege escalation capabilities.
Mitigation strategies for CVE-2018-14854 require both immediate patching and defensive measures to protect against exploitation attempts. Samsung released security patches for affected Galaxy S6 devices through their regular security update cycles, which users should install immediately to address the vulnerability. The patch likely involves implementing proper bounds checking and input validation within the dhd_bus_flow_ring_delete_response function to prevent buffer overflows when processing flow ring delete responses. Organizations should also consider implementing network-level monitoring to detect unusual Wi-Fi traffic patterns that might indicate exploitation attempts, particularly in enterprise environments where these devices might be used. Device hardening measures including kernel module signing, secure boot implementations, and runtime protection mechanisms can help prevent exploitation even if the vulnerability remains unpatched. The vulnerability demonstrates the importance of secure coding practices in kernel space drivers and highlights the need for comprehensive security reviews of all device drivers, particularly those implementing complex PCIe communication protocols. Additionally, implementing network segmentation and access control measures can limit the potential impact of exploitation attempts, while regular security assessments of mobile device firmware can help identify similar vulnerabilities before they can be exploited by attackers.