CVE-2019-9377 in Android
Summary
by MITRE
In FingerprintService, there is a possible bypass for operating system protections that isolate user profiles from each other due to a missing permission check. This could lead to a local information disclosure of metadata about the biometrics of another user on the device with no additional execution privileges needed. User interaction is not needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-128599663
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability identified as CVE-2019-9377 resides within the FingerprintService component of Android operating systems, specifically affecting Android 10 and earlier versions. This issue represents a critical breakdown in the operating system's security model that governs user profile isolation and biometric data protection. The flaw manifests as a missing permission check within the fingerprint service that should enforce proper access controls between distinct user profiles on the same device. The vulnerability is particularly concerning because it allows for unauthorized access to biometric metadata without requiring any additional privileges or user interaction, making it an attractive target for attackers seeking to exploit device security boundaries. This weakness directly undermines the fundamental security principle that user profiles should remain isolated from one another, creating a potential pathway for information disclosure across user contexts.
The technical nature of this vulnerability stems from insufficient authorization checks within the FingerprintService implementation. When multiple user profiles exist on an Android device, the system should enforce strict permissions to prevent one user from accessing another user's biometric data or metadata. However, the missing permission check in this implementation allows a malicious process or application to bypass these protective mechanisms and retrieve fingerprint-related information from other user profiles. The flaw operates at the system level where fingerprint service components handle biometric data management, making it particularly dangerous as it can be exploited by any local process with minimal privileges. This represents a classic case of inadequate access control that aligns with CWE-284, which addresses improper access control issues in software systems. The vulnerability's exploitation requires no user interaction, meaning it can be triggered automatically by malicious code running on the device, and the attack vector is purely local to the device itself.
The operational impact of CVE-2019-9377 extends beyond simple information disclosure, as biometric metadata can provide attackers with valuable insights into user behavior patterns and device usage. While the vulnerability specifically targets metadata rather than raw biometric templates, this information can still be used to construct profiles of user activities and potentially aid in social engineering attacks. The local nature of the exploit means that attackers do not need network connectivity or external tools to leverage this vulnerability, making it particularly dangerous in environments where devices may be compromised through other attack vectors. This weakness creates a persistent threat that can be exploited even after initial compromise, as the vulnerability exists within core system services that are typically not subject to frequent updates or patches. From an attacker's perspective, this vulnerability aligns with techniques described in the ATT&CK framework under the T1056 category for input injection, though it operates more specifically within the realm of privilege escalation and credential access.
Mitigation strategies for CVE-2019-9377 should focus on immediate patch deployment through official Android security updates, as this vulnerability was addressed in subsequent Android releases. Organizations and device manufacturers must ensure that all affected devices receive timely security updates to remediate the missing permission check in FingerprintService. System administrators should implement comprehensive monitoring for unauthorized access attempts to biometric services and consider additional security controls such as enhanced application sandboxing and stricter permission management policies. The vulnerability highlights the importance of proper access control implementation in system-level services and demonstrates how seemingly minor oversights in permission checking can create significant security risks. Security teams should also consider conducting thorough audits of other system services to identify similar permission bypass vulnerabilities that might exist in the operating system's security model. Additionally, users should be educated about the importance of keeping devices updated and understanding the risks associated with unauthorized applications that might attempt to exploit such vulnerabilities in the future.