CVE-2019-9269 in Android
Summary
by MITRE
In System Settings, there is a possible permissions bypass due to a cached Linux user ID. This could lead to a local permissions bypass with no additional execution privileges needed. User interaction is needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-36899497
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Analysis
by VulDB Data Team • 09/12/2020
The vulnerability identified as CVE-2019-9269 represents a significant security flaw within Android's System Settings component that exploits a cached Linux user ID to bypass local permissions. This issue resides in the Android 10 operating system and is tracked under Android ID A-36899497, demonstrating how seemingly minor implementation details can create substantial security risks. The vulnerability specifically affects the permission handling mechanisms within the system settings interface, where cached user identifiers are improperly validated during access control decisions.
The technical root cause of this vulnerability stems from improper validation of cached Linux user IDs within the Android system settings framework. When system settings are accessed, the application caches user identifiers to optimize performance and reduce redundant authentication checks. However, this caching mechanism fails to properly verify the legitimacy of cached identifiers, allowing malicious actors to exploit this weakness through carefully crafted user interactions. The flaw operates at the intersection of Linux user privilege management and Android's permission model, creating an environment where cached credentials can be reused or manipulated to gain unauthorized access to system resources.
From an operational impact perspective, this vulnerability enables a local permissions bypass that requires no additional execution privileges beyond normal user access. The attack vector necessitates user interaction, which means that exploitation typically occurs through social engineering or user deception rather than automated attacks. However, the implications are severe as it allows attackers to potentially access system settings and resources that should be restricted to specific user roles or administrative privileges. This creates opportunities for privilege escalation and unauthorized modification of system configurations that could compromise device security and data integrity.
The vulnerability aligns with CWE-284, which addresses improper access control in software systems, and demonstrates how cached data validation failures can undermine security controls. From an ATT&CK framework perspective, this issue relates to privilege escalation techniques and can be categorized under T1068, which covers "Exploitation for Privilege Escalation." The attack requires minimal technical expertise to execute, making it particularly dangerous as it can be exploited by adversaries with basic knowledge of Android system behavior. The cached user ID mechanism represents a classic example of how performance optimization features can introduce security vulnerabilities when proper validation checks are omitted.
Mitigation strategies for this vulnerability should focus on implementing proper validation of cached identifiers before granting access to system resources. System administrators should ensure that Android devices are updated to versions that address this specific flaw, as Google typically releases security patches for such issues. Additionally, organizations should consider implementing monitoring solutions that can detect unauthorized access attempts to system settings and user privilege modifications. The recommended approach involves strengthening the validation process for cached identifiers and ensuring that all cached data is properly authenticated before being used in access control decisions. Regular security audits of system settings and user privilege management mechanisms should also be conducted to identify potential similar vulnerabilities in other components of the Android ecosystem.