CVE-2019-20584 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with O(8.x) and P(9.0) (with TEEGRIS) software. There is type confusion in the HDCP Trustlet, leading to arbitrary code execution. The Samsung ID is SVE-2019-14850 (August 2019).
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Analysis
by VulDB Data Team • 10/04/2020
The vulnerability CVE-2019-20584 represents a critical type confusion flaw within the HDCP Trustlet component of Samsung's mobile devices running Android 8.x and 9.0 operating systems with TEEGRIS security framework. This issue resides in the hardware-based cryptographic protection mechanism that governs high-bandwidth digital content protection, which is essential for securing digital media transmission between devices. The HDCP Trustlet operates within the Trusted Execution Environment, making it a critical security component that handles sensitive cryptographic operations and digital rights management functions. The vulnerability specifically manifests in the trustlet's handling of data types during processing, where improper type validation allows for memory corruption that can be exploited by malicious actors.
The technical exploitation of this vulnerability stems from a type confusion error in the Trustlet's memory management routines, where the system fails to properly validate data types before processing operations. This type confusion allows an attacker to manipulate memory layout and execute arbitrary code with elevated privileges within the Trustlet environment. The vulnerability's impact is amplified by the fact that it operates within the TEEGRIS framework, which provides a secure execution environment for sensitive operations. According to CWE-466, this represents a specific instance of improper handling of type information, where the system incorrectly processes data types that should be strictly validated. The attack vector typically involves crafting malicious input that tricks the Trustlet into interpreting data as a different type than intended, leading to memory corruption and potential privilege escalation.
The operational impact of CVE-2019-20584 extends beyond simple code execution, as it compromises the fundamental security guarantees provided by the HDCP Trustlet and the broader TEEGRIS framework. This vulnerability enables attackers to bypass hardware-based security measures that protect digital content and cryptographic keys, potentially allowing unauthorized access to protected media content and sensitive cryptographic operations. The exploitation can result in complete compromise of the device's secure element, as demonstrated by the ATT&CK framework's T1059.007 technique for command and scripting interpreter, where the arbitrary code execution enables further attack progression. Samsung's security advisory SVE-2019-14850 indicates that this vulnerability affects devices with specific TEEGRIS implementations, making it particularly concerning for enterprise and consumer devices that rely on hardware security for content protection and secure transactions.
Mitigation strategies for this vulnerability require immediate firmware updates from Samsung, as the fix typically involves patching the Trustlet's type validation routines and strengthening memory management protocols. Security teams should implement network-based monitoring to detect potential exploitation attempts targeting the HDCP Trustlet, particularly focusing on unusual memory access patterns and privilege escalation attempts. The vulnerability's classification under CWE-466 necessitates comprehensive code review of all Trustlet components, with particular attention to type handling and memory validation mechanisms. Organizations should also consider implementing device management policies that enforce immediate security updates and monitor for unauthorized modifications to secure elements. Additionally, the mitigation approach should align with NIST SP 800-53 security controls, specifically focusing on system and information integrity controls that protect against unauthorized code execution and maintain the integrity of trusted execution environments.