CVE-2019-20545 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with O(8.x) and P(9.0) (Exynos chipsets) software. A buffer overflow in the HDCP Trustlet affects secure TEEGRIS memory. The Samsung ID is SVE-2019-15283 (November 2019).
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Analysis
by VulDB Data Team • 10/04/2020
This vulnerability represents a critical buffer overflow flaw within the HDCP Trustlet component of Samsung's mobile device firmware, specifically impacting devices running on Exynos chipsets with Android operating system versions 8.x and 9.0. The issue resides in the secure TEEGRIS memory region, which serves as a critical security boundary for protecting sensitive cryptographic operations and secure data processing. The HDCP Trustlet is responsible for handling High-bandwidth Digital Content Protection protocols that are essential for secure video output and content protection mechanisms in mobile devices. This vulnerability demonstrates a fundamental flaw in Samsung's secure element implementation where improper bounds checking allows malicious actors to potentially overwrite adjacent memory regions within the trusted execution environment.
The technical exploitation of this buffer overflow occurs when the HDCP Trustlet processes malformed input data without adequate validation, leading to memory corruption that can be leveraged to execute arbitrary code within the secure memory space. This represents a severe breach of the Trusted Execution Environment's integrity, as the TEEGRIS memory is designed to maintain isolation from the main operating system and prevent unauthorized access to sensitive cryptographic keys, secure boot processes, and other critical security functions. The vulnerability specifically targets the memory management controls that govern how data flows between the normal world and the secure world of the TEE, creating potential pathways for privilege escalation attacks that could compromise the entire device security architecture.
The operational impact of this vulnerability extends beyond simple local exploitation, as it affects a significant number of Samsung devices that rely on Exynos chipsets for their secure processing capabilities. Attackers could potentially leverage this flaw to bypass secure boot mechanisms, extract cryptographic keys from the secure memory, or gain unauthorized access to protected content and data processing functions. The vulnerability's classification as a buffer overflow aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a direct threat to the device's security model. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and secure boot bypass, with potential for lateral movement within the device's secure processing environment.
Mitigation strategies for this vulnerability require immediate firmware updates from Samsung, as the issue resides in the device's core security infrastructure rather than in user applications. System administrators and device manufacturers should implement comprehensive security monitoring to detect anomalous behavior in the TEEGRIS memory regions and establish proper input validation controls for all HDCP Trustlet operations. The vulnerability highlights the importance of robust memory management practices in secure environments and underscores the need for regular security assessments of trusted execution environments. Additionally, organizations should consider implementing device-specific security policies that restrict access to secure memory regions and establish proper network segmentation to prevent lateral movement in case of successful exploitation attempts.