CVE-2019-20588 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 SEM Trustlet, leading to arbitrary code execution. The Samsung ID is SVE-2019-14891 (August 2019).
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Analysis
by VulDB Data Team • 10/04/2020
The vulnerability CVE-2019-20588 represents a critical type confusion flaw within Samsung's Secure Element Manager Trustlet implementation on Android 8.0 and 9.0 devices that utilize the TEEGRIS security framework. This issue manifests in the SEM Trustlet component which serves as a crucial security service running within the Trusted Execution Environment, responsible for managing secure operations and cryptographic functions. The vulnerability was identified and documented by Samsung under their internal tracking system SVE-2019-14891, highlighting the severity of the flaw that affects a significant portion of Samsung's smartphone fleet during the 2019 security cycle.
The technical root cause of this vulnerability stems from improper type validation within the SEM Trustlet's input handling mechanisms, creating a type confusion scenario that allows attackers to manipulate data structures in unexpected ways. This type confusion occurs when the trustlet processes user-supplied data without adequate type checking, enabling an attacker to craft malicious inputs that cause the system to interpret data as different types than intended. The flaw specifically impacts the memory management and object handling within the secure execution environment, where the trustlet's code fails to properly validate the types of parameters passed to its functions, potentially leading to memory corruption and control flow manipulation.
The operational impact of this vulnerability is severe as it enables arbitrary code execution within the Trusted Execution Environment, which is designed to provide a secure sandbox for sensitive operations. Attackers who successfully exploit this vulnerability can bypass the security boundaries that separate normal operating system processes from trusted security services, potentially gaining access to cryptographic keys, secure storage, and other sensitive data managed by the SEM Trustlet. This arbitrary code execution capability allows for privilege escalation attacks that can compromise the entire security architecture of the device, making it particularly dangerous for mobile devices where the TEE is expected to provide robust protection against malicious software and unauthorized access attempts.
Mitigation strategies for this vulnerability require immediate patching of affected Samsung devices through official security updates, as the flaw exists within the core security infrastructure of the device. Organizations should implement comprehensive device management policies to ensure timely deployment of security patches across all affected Samsung devices within their inventory. The vulnerability aligns with CWE-471, which describes the weakness of "Incorrectly Handling of Type Confusion" in software implementations, and maps to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript' and T1068 for 'Exploitation for Privilege Escalation', demonstrating how attackers could leverage this flaw to gain elevated privileges and execute malicious code within the secure execution environment. System administrators should also consider implementing network-based monitoring to detect potential exploitation attempts targeting this specific vulnerability, as the attack surface extends beyond local execution to include potential remote exploitation vectors through malicious applications or services that interact with the affected trustlet components.