CVE-2018-21049 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with N(7.x) and O(8.X) (Exynos chipsets) software. There is an arbitrary memory write in a Trustlet because a secure driver allows access to sensitive APIs. The Samsung ID is SVE-2018-12881 (November 2018).
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Analysis
by VulDB Data Team • 10/07/2020
The vulnerability identified as CVE-2018-21049 represents a critical security flaw affecting Samsung mobile devices running Android Nougat 7.x and Oreo 8.x operating systems, specifically those utilizing Exynos chipsets. This issue resides within the Trustlet component of Samsung's Secure Element architecture, which serves as a critical security layer responsible for protecting sensitive operations and data processing. The vulnerability stems from improper access controls within a secure driver that governs interactions between the trusted execution environment and the main operating system, creating a dangerous pathway for privilege escalation attacks.
The technical flaw manifests as an arbitrary memory write condition that occurs when a secure driver fails to properly validate input parameters before granting access to sensitive Application Programming Interfaces. This allows malicious actors to write arbitrary data to memory locations that should remain protected, effectively bypassing the security boundaries that separate trusted and untrusted execution environments. The vulnerability is categorized under CWE-787: "Out-of-bounds Write" and represents a direct violation of memory safety principles that are fundamental to secure system design. The flaw exists in the Trustlet implementation, which is a small secure application that runs within the Trusted Execution Environment and handles critical security operations.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the capability to execute arbitrary code within the secure environment with elevated privileges. This compromises the integrity of the entire device security architecture, potentially allowing attackers to extract sensitive cryptographic keys, bypass authentication mechanisms, and gain access to protected user data. The vulnerability affects devices that rely on Exynos chipsets, which are prevalent in Samsung's flagship smartphone lineup, making it a widespread concern across multiple device models. According to ATT&CK framework category T1068, this vulnerability enables privilege escalation and can be leveraged for lateral movement within the device's security boundaries, while T1547.001 indicates potential persistence mechanisms that could be established through this flaw.
Mitigation strategies for CVE-2018-21049 require immediate action through official security updates provided by Samsung, as the vulnerability cannot be effectively addressed through user-level configuration changes or third-party security solutions. The patch implementation involves strengthening the secure driver's input validation mechanisms and ensuring proper access controls are enforced before sensitive APIs are exposed to untrusted code paths. Organizations and individuals should prioritize applying the Samsung security patches released in November 2018, which addressed the specific Trustlet access control issues. Additionally, system administrators should consider implementing device management policies that enforce automatic security updates and monitor for any unauthorized modifications to the secure execution environment. The vulnerability demonstrates the critical importance of secure boot processes and proper isolation mechanisms in mobile security architectures, as highlighted by industry standards such as the NIST Cybersecurity Framework and ISO/IEC 27001 security controls.