CVE-2016-3851 in Android
Summary
by MITRE
The LG Electronics bootloader Android before 2016-08-05 on Nexus 5X devices allows attackers to gain privileges by leveraging access to a privileged process, aka internal bug 29189941.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/20/2019
The vulnerability identified as CVE-2016-3851 represents a critical privilege escalation flaw within the bootloader implementation of LG Electronics Android devices, specifically affecting Nexus 5X models prior to the 2016-08-05 security update. This vulnerability resides in the boot process where the system fails to properly validate access controls for privileged operations, creating an exploitable condition that allows malicious actors to elevate their privileges from standard user level to system-level access. The flaw specifically targets the bootloader component which serves as the first line of defense in the device's security architecture, making it a prime target for attackers seeking persistent control over the affected devices.
The technical exploitation of this vulnerability occurs through the manipulation of access controls within the privileged process environment that governs the bootloader's operation. Attackers can leverage existing access to a privileged process to bypass normal security boundaries and execute code with elevated privileges. This mechanism aligns with CWE-284, which describes improper access control vulnerabilities where an attacker can gain unauthorized access to resources or capabilities. The vulnerability demonstrates a classic case of insufficient privilege checking during boot sequence operations, where the system fails to properly enforce the principle of least privilege that should prevent unauthorized elevation of privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with persistent access to the device's core system functions and data storage. Once exploited, the attacker can modify system files, install malicious applications, access encrypted data, and potentially establish backdoors that survive device reboots. The Nexus 5X platform, being a widely deployed device, amplifies the potential attack surface significantly. This vulnerability enables attackers to perform operations that would normally require physical access or specialized tools, effectively compromising the device's security model. The impact is particularly severe in enterprise environments where such devices might be used for sensitive data processing or communication.
Mitigation strategies for CVE-2016-3851 focus primarily on applying the security patches released by LG Electronics and Google, which address the bootloader access control flaws through proper privilege validation mechanisms. System administrators should prioritize immediate deployment of the August 2016 security update that includes fixes for this vulnerability. Additionally, organizations should implement device management policies that enforce regular security updates and monitor for unauthorized modifications to device firmware. The vulnerability also highlights the importance of secure boot processes and proper implementation of access control mechanisms during early boot phases, as outlined in the NIST Cybersecurity Framework for mobile device security. Network-level monitoring should be enhanced to detect anomalous behavior that might indicate exploitation attempts, while device enrollment in trusted platform modules can provide additional protection against unauthorized firmware modifications. This vulnerability serves as a reminder of the critical importance of securing boot processes and maintaining up-to-date security patches across all device components, as documented in the ATT&CK framework's boot and recovery process techniques that attackers frequently target for persistent access.