CVE-2018-21066 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with M(6.0) (Exynos or MediaTek chipsets) software. There is a buffer overflow in a Trustlet that can cause memory corruption. The Samsung ID is SVE-2018-11599 (July 2018).
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Analysis
by VulDB Data Team • 10/07/2020
This vulnerability represents a critical buffer overflow condition within the Trustlet component of Samsung mobile devices running Android 6.0 operating system with either Exynos or MediaTek chipsets. The Trustlet environment serves as a secure execution environment that handles sensitive operations and cryptographic functions, making this flaw particularly concerning from a security perspective. The buffer overflow occurs in the trustlet implementation where insufficient bounds checking allows an attacker to write beyond allocated memory boundaries, potentially leading to arbitrary code execution within the secure environment.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. These classifications indicate that the flaw stems from improper memory management within the trustlet execution context where input validation is inadequate. The vulnerability specifically affects the secure element processing within Samsung's mobile platform, where Trustlets operate in a privileged mode separate from the main operating system. This architectural design is intended to protect sensitive operations but becomes a security risk when memory corruption vulnerabilities exist within the trustlet implementation itself.
The operational impact of this vulnerability extends beyond simple memory corruption as it can be exploited to gain elevated privileges within the secure execution environment. Attackers could potentially leverage this flaw to execute malicious code with the same privileges as the trustlet, which typically includes access to cryptographic keys, secure storage, and other sensitive operations. This represents a significant escalation from standard mobile application attacks to attacks targeting the underlying security infrastructure. The vulnerability affects devices with specific hardware configurations, particularly those using Exynos or MediaTek chipsets, which limits its scope but makes it particularly dangerous for the affected user base. The Samsung security advisory SVE-2018-11599 indicates that this vulnerability was addressed through firmware updates that included memory bounds checking improvements and proper input validation within the trustlet components.
From an adversary perspective, this vulnerability maps to several ATT&CK techniques including privilege escalation and defense evasion. The attack chain would typically involve exploiting the buffer overflow to gain code execution within the trustlet environment, followed by leveraging the elevated privileges to access sensitive data or modify secure operations. The trustlet environment's design is intended to provide isolation from the main operating system, but this vulnerability undermines that security boundary. Mitigation strategies should include immediate firmware updates from Samsung, which would address the specific memory handling issues within the trustlet implementation. Additionally, device manufacturers should implement runtime protections such as stack canaries and address space layout randomization to make exploitation more difficult. The vulnerability highlights the importance of secure coding practices in trusted execution environments and demonstrates how flaws in security-critical components can have far-reaching consequences for overall device security.