CVE-2018-5210 in Samsung
Summary
by MITRE
On Samsung mobile devices with N(7.x) software and Exynos chipsets, attackers can conduct a Trustlet stack overflow attack for arbitrary TEE code execution, in conjunction with a brute-force attack to discover unlock information (PIN, password, or pattern). The Samsung ID is SVE-2017-10733.
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Analysis
by VulDB Data Team • 12/19/2019
The vulnerability CVE-2018-5210 represents a critical security flaw affecting Samsung mobile devices running Android 7.x software with Exynos chipsets. This vulnerability resides within the Trustlet component of Samsung's Trusted Execution Environment implementation, creating a pathway for attackers to execute arbitrary code within the TEE context. The flaw manifests as a stack buffer overflow condition that can be exploited through carefully crafted inputs to the Trustlet service, potentially allowing full compromise of the secure element that handles sensitive operations such as biometric authentication, cryptographic key storage, and secure boot processes.
The technical exploitation of this vulnerability follows a multi-stage attack pattern that combines local privilege escalation with additional attack vectors to bypass device security measures. The stack overflow occurs within the Trustlet execution environment, which operates in a separate secure memory space from the main Android operating system. This architectural separation is designed to protect sensitive operations, but the overflow vulnerability allows attackers to overwrite critical memory locations and redirect execution flow. The vulnerability is particularly concerning because it operates at a low system level where traditional Android security mechanisms may not fully apply, and it can potentially be leveraged to gain access to the device's secure storage, which contains encryption keys, biometric templates, and other sensitive data.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to perform brute-force attacks against device unlock mechanisms including PIN, password, and pattern protections. This combination creates a particularly dangerous attack scenario where an attacker can first exploit the Trustlet overflow to gain code execution privileges within the TEE, then use this elevated access to bypass or circumvent device lock screens and authentication mechanisms. The vulnerability affects devices that rely on Samsung's Keystore system and Secure Element implementation, which are fundamental components for protecting user data and maintaining device integrity. The attack requires local access to the device but can potentially be executed without user interaction once the initial Trustlet overflow is successfully exploited, making it a significant threat to device security and user privacy.
The attack vector for CVE-2018-5210 typically involves crafting malicious inputs that trigger the buffer overflow condition within the Trustlet service, which operates with elevated privileges in the TEE environment. This vulnerability aligns with CWE-121 Stack-based Buffer Overflow, a well-documented weakness that occurs when data is written beyond the bounds of a fixed-length buffer allocated on the stack. The exploitation process may involve multiple steps including memory layout analysis, payload delivery, and execution control manipulation to achieve persistent access to the secure environment. Security researchers have noted that this vulnerability can be particularly challenging to detect and mitigate due to its location within the TEE, which operates outside the normal Android security boundaries and is designed to provide isolation from the main operating system.
Organizations and users should implement immediate mitigations including applying available security patches from Samsung, which typically address the specific Trustlet overflow condition through code updates and memory protection enhancements. Device administrators should consider disabling unnecessary Trustlet services and implementing additional security monitoring to detect anomalous behavior within the secure execution environment. The vulnerability demonstrates the importance of secure coding practices within TEE implementations and highlights the need for comprehensive security testing of trusted execution environments. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and credential access, specifically targeting the TEE environment to bypass traditional Android security controls. Regular security assessments should include evaluation of TEE implementations and their susceptibility to buffer overflow conditions, particularly in mobile environments where device security is paramount for protecting sensitive user information and maintaining trust in mobile computing platforms.