CVE-2018-21063 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with M(6.0), N(7.x), and O(8.x) (Exynos chipsets) software. Keymaster has an architectural problem because tlApi in TEE is not properly protected. The Samsung ID is SVE-2018-11792 (August 2018).
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Analysis
by VulDB Data Team • 10/07/2020
The vulnerability identified as CVE-2018-21063 represents a critical security flaw in Samsung mobile devices running Android versions 6.0, 7.x, and 8.x that utilize Exynos chipsets. This issue specifically targets the Trusted Execution Environment (TEE) component of the device's security architecture, where the Keymaster service fails to adequately protect the tlApi interface within the TEE environment. The architectural weakness stems from insufficient isolation mechanisms that allow unauthorized access to sensitive cryptographic operations and key management functions. This vulnerability was catalogued under Samsung's internal tracking system as SVE-2018-11792 and was disclosed in August 2018, highlighting the critical nature of TEE protection mechanisms in mobile security infrastructures.
The technical flaw manifests in the improper protection of the tlApi interface within the Trusted Execution Environment, which serves as a critical communication channel between the secure world and the normal world of the device's operating system. This architectural deficiency allows malicious actors to potentially exploit the unprotected interface to gain unauthorized access to cryptographic keys and sensitive operations within the TEE. The vulnerability specifically affects devices with Exynos chipsets, indicating a chipset-specific implementation issue rather than a generic Android security problem. The tlApi interface, which should maintain strict security boundaries between different execution environments, fails to enforce proper access controls and authentication mechanisms that are fundamental requirements for TEE integrity according to common security architecture principles.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it compromises the fundamental security guarantees that users expect from their mobile devices. Attackers could potentially extract cryptographic keys, perform unauthorized cryptographic operations, or manipulate secure key storage mechanisms that are supposed to remain isolated from the main operating system. This vulnerability directly affects the security of sensitive data protection, secure authentication mechanisms, and the overall integrity of the device's cryptographic infrastructure. The implications are particularly severe given that these devices run on widely deployed Android versions and chipsets, affecting millions of users across multiple device generations. The vulnerability enables potential attackers to bypass hardware-based security features and could lead to complete compromise of the device's secure element functionality.
Mitigation strategies for this vulnerability should focus on immediate software updates from Samsung to address the TEE protection mechanisms and ensure proper isolation of the tlApi interface. Organizations and users should prioritize installing the latest security patches released by Samsung, as these updates typically include enhanced protection mechanisms for the TEE components. System administrators should implement comprehensive device monitoring to detect any unauthorized access attempts or abnormal behavior patterns that might indicate exploitation attempts. Additionally, the vulnerability highlights the importance of robust TEE design principles and adherence to security standards such as those outlined in the Common Weakness Enumeration (CWE) catalog, specifically CWE-284 which addresses improper access control in security contexts. The ATT&CK framework would classify this vulnerability under privilege escalation techniques, potentially enabling lateral movement and persistent access within compromised devices, making proper patch management and device security monitoring critical defensive measures.