CVE-2019-20586 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with O(8.1) and P(9.0) (with TEEGRIS) software. There is type confusion in the FINGERPRINT Trustlet, leading to arbitrary code execution. The Samsung ID is SVE-2019-14864 (August 2019).
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Analysis
by VulDB Data Team • 10/04/2020
The vulnerability CVE-2019-20586 represents a critical type confusion flaw within the FINGERPRINT Trustlet component of Samsung's TEEGRIS security architecture on Android 8.1 and 9.0 devices. This issue resides within the Trusted Execution Environment (TEE) where fingerprint authentication processing occurs, making it particularly dangerous as it operates in a security-sensitive context separate from the main operating system. The vulnerability was identified and tracked by Samsung under the internal identifier SVE-2019-14864, highlighting the manufacturer's recognition of its severity within their own security assessment framework.
Type confusion vulnerabilities occur when a program incorrectly handles data types during execution, leading to memory corruption that can be exploited to gain unauthorized control over system operations. In this case, the FINGERPRINT Trustlet's handling of input parameters fails to properly validate type information, creating a scenario where an attacker can manipulate the trustlet's execution flow through carefully crafted fingerprint data. This flaw operates at the intersection of hardware security modules and software trustlets, where proper type checking mechanisms are essential to maintain the integrity of the secure element. The vulnerability specifically affects devices running Samsung's TEEGRIS implementation, which provides a secure environment for biometric authentication processing.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables arbitrary code execution within the TEE environment where sensitive biometric data and authentication keys are processed. Attackers could potentially exploit this flaw to bypass fingerprint authentication mechanisms, gain access to secure storage areas, or even escalate privileges to full system control. The TEE environment is designed to be isolated from the main Android OS, making such vulnerabilities particularly concerning as they represent a compromise of the fundamental security architecture. This type of vulnerability directly impacts the Confidentiality, Integrity, and Availability (CIA) triad of security principles, particularly affecting the integrity of the biometric authentication system and potentially compromising the entire device security model.
Mitigation strategies for CVE-2019-20586 should prioritize immediate patch deployment through Samsung's security update mechanisms, as the vulnerability affects devices that were widely deployed in consumer markets. Organizations and individuals should ensure their Samsung devices receive the appropriate security patches released by Samsung, which typically address the underlying type confusion issue through proper input validation and type checking mechanisms. The fix likely involves strengthening parameter validation within the FINGERPRINT Trustlet and implementing additional safeguards against improper type handling. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1548.002 (Abuse Elevation Control Mechanism) and CWE-466 (Return of Pointer Type) or CWE-471 (Incorrect Handling of Pointer Type), demonstrating how type confusion can lead to privilege escalation and system compromise. Security teams should also monitor for potential exploitation attempts in the wild and consider implementing additional device monitoring to detect abnormal behavior in the TEE environment.