CVE-2018-14855 in Galaxy S6
Summary
by MITRE
Buffer overflow in dhd_bus_flow_ring_flush_response in drivers/net/wireless/bcmdhd4358/dhd_pcie.c in the bcmdhd4358 Wi-Fi driver on the Samsung Galaxy S6 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-2018-14855 represents a critical buffer overflow condition within the bcmdhd4358 Wi-Fi driver component of Samsung Galaxy S6 devices, specifically within the dhd_bus_flow_ring_flush_response function located in drivers/net/wireless/bcmdhd4358/dhd_pcie.c. This flaw exists in the PCIe implementation of the Broadcom Wi-Fi driver stack and constitutes a direct violation of the fundamental memory safety principles that govern secure software development practices. The vulnerability manifests when the driver processes flow ring flush responses, creating a scenario where attacker-controlled data can overflow allocated buffer space and overwrite adjacent memory regions.
The technical implementation of this vulnerability stems from inadequate bounds checking within the driver's response processing logic. When the dhd_bus_flow_ring_flush_response function handles incoming PCIe communication from the Wi-Fi chip, it fails to validate the size or contents of the data being processed against the allocated buffer boundaries. This insufficient input validation creates an exploitable condition where malicious data can be injected into the driver's memory space, potentially allowing arbitrary code execution within the kernel context. The vulnerability is particularly concerning because it requires only code execution capability on the Wi-Fi chip itself, which can be achieved through sophisticated supply chain attacks or other advanced persistent threat techniques.
The operational impact of CVE-2018-14855 extends beyond simple denial of service scenarios, as it enables privilege escalation from user-mode to kernel-mode execution context. An attacker who has already compromised the Wi-Fi chip's execution environment can leverage this buffer overflow to execute arbitrary code with kernel-level privileges, potentially leading to complete device compromise. This vulnerability directly aligns with attack patterns described in the MITRE ATT&CK framework under the privilege escalation and persistence domains, specifically targeting kernel-mode vulnerabilities that allow attackers to maintain long-term access to mobile devices. The Samsung-specific identifier SVE-2018-11785 indicates this was recognized as a significant security concern within Samsung's vulnerability management system.
Mitigation strategies for CVE-2018-14855 should focus on both immediate patching and broader defensive measures. The primary remediation involves applying the vendor-provided security patch that corrects the buffer overflow condition through proper bounds checking and memory allocation validation. Organizations should also implement network-based monitoring to detect anomalous Wi-Fi chip behavior that might indicate exploitation attempts. Additionally, the vulnerability highlights the importance of secure coding practices and adherence to CWE guidelines, particularly CWE-121 which addresses stack-based buffer overflow conditions. Device manufacturers should consider implementing runtime protection mechanisms and memory corruption detection systems to prevent exploitation attempts, while security researchers should monitor for similar vulnerabilities in other Broadcom Wi-Fi driver implementations that may share similar architectural flaws.