CVE-2018-21052 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 incorrect usage of shared memory in the vaultkeeper Trustlet, leading to arbitrary code execution. The Samsung ID is SVE-2018-12855 (October 2018).
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Analysis
by VulDB Data Team • 10/07/2020
The vulnerability identified as CVE-2018-21052 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 vaultkeeper Trustlet component, which serves as a security module responsible for protecting sensitive cryptographic operations and secure storage mechanisms. The vulnerability stems from improper handling of shared memory resources within this trustlet environment, creating a pathway for malicious actors to execute arbitrary code on affected devices. The Samsung security advisory SVE-2018-12855 documented this weakness, highlighting its potential to compromise the integrity of the device's security architecture. The flaw specifically impacts the trustlet's memory management practices, where shared memory segments are not properly validated or isolated, allowing unauthorized code execution within the secure execution environment.
Technical exploitation of this vulnerability occurs through manipulation of shared memory operations within the vaultkeeper Trustlet, which operates in a privileged security context separate from regular Android applications. The improper memory usage creates a condition where an attacker can potentially overwrite memory locations or inject malicious code into the trustlet's execution space. This type of vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios, though the specific implementation involves shared memory corruption rather than traditional buffer overflows. The vulnerability exists because the Trustlet implementation fails to properly validate memory access patterns and does not implement adequate memory isolation mechanisms between different memory segments. Attackers can leverage this weakness to bypass security boundaries and gain elevated privileges within the secure execution environment, potentially accessing protected cryptographic keys or sensitive user data.
The operational impact of CVE-2018-21052 extends beyond simple privilege escalation, as it fundamentally compromises the security model of Samsung's mobile platform. Devices affected by this vulnerability become susceptible to attacks that can extract cryptographic keys used for secure communications, authentication tokens, or other sensitive data stored within the Trustlet's secure memory space. This weakness enables sophisticated attacks such as those targeting the device's secure element, potentially allowing for complete device compromise or unauthorized access to encrypted data. The vulnerability affects the fundamental security architecture of Samsung's Exynos-based devices, undermining the trust model that relies on isolated execution environments for protecting sensitive operations. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion, as attackers can leverage the trustlet's legitimate access to bypass security controls. The impact is particularly severe given that the Trustlet operates in a privileged security context, making it a prime target for attackers seeking to establish persistent access or extract sensitive cryptographic material.
Mitigation strategies for CVE-2018-21052 require immediate implementation of Samsung security patches and updates, as the vulnerability exists within the device's firmware and requires system-level remediation. Users should ensure their devices receive the latest security updates from Samsung, particularly those addressing the vaultkeeper Trustlet implementation and shared memory management. Organizations deploying Samsung devices in enterprise environments should implement comprehensive device management policies to ensure timely patch deployment and monitor for signs of exploitation attempts. The vulnerability highlights the importance of proper memory management in secure execution environments and underscores the need for rigorous security testing of trustlet implementations. System administrators should consider implementing network monitoring to detect potential exploitation attempts and establish incident response procedures specifically addressing Trustlet-based vulnerabilities. Security teams should also conduct thorough vulnerability assessments of other trustlet implementations within the device's security architecture to identify similar memory management issues that could present analogous risks.