CVE-2020-0439 in Android
Summary
by MITRE • 11/10/2020
In generatePackageInfo of PackageManagerService.java, there is a possible permissions bypass due to an incorrect permission check. This could lead to local escalation of privilege that allows instant apps access to permissions not allowed for instant apps, with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-8.1 Android-9 Android-10 Android-11 Android-8.0Android ID: A-140256621
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Analysis
by VulDB Data Team • 12/04/2020
The vulnerability described in CVE-2020-0439 represents a critical permissions bypass flaw within Android's package management system that affects multiple Android versions including 8.0, 8.1, 9, 10, and 11. This issue resides in the generatePackageInfo method of PackageManagerService.java, which serves as a fundamental component in Android's security architecture responsible for managing application package information and permissions. The flaw stems from an incorrect permission check implementation that fails to properly validate access controls for instant applications, creating a pathway for malicious actors to escalate privileges and gain unauthorized access to restricted permissions that should be denied to instant apps by design.
The technical implementation of this vulnerability involves a flaw in the permission validation logic where the system incorrectly grants permissions to instant applications that should be restricted based on their temporary nature and security model. This misconfiguration allows instant apps to bypass the normal permission gating mechanisms that typically prevent them from accessing sensitive system resources or performing privileged operations. The vulnerability specifically targets the package information generation process where the system should enforce strict permission boundaries between regular applications and instant applications, but instead permits unauthorized access through a flawed validation routine.
From an operational perspective, this vulnerability enables local privilege escalation without requiring any user interaction or additional execution privileges, making it particularly dangerous as it can be exploited silently in the background. The impact extends beyond simple permission bypass to potentially allow instant applications to access sensitive data, perform system-level operations, or gain access to other applications' resources that should remain protected. This represents a fundamental breakdown in Android's security model where the boundary between temporary and permanent application permissions becomes porous, creating opportunities for malicious code to leverage instant app capabilities for unauthorized system access.
The vulnerability aligns with CWE-284 which addresses improper access control issues, specifically focusing on insufficient permission checks within system services. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques where adversaries can leverage system service flaws to gain elevated privileges. The attack vector requires no user interaction, making it particularly concerning as it can be exploited automatically without victim awareness, potentially allowing for stealthy privilege escalation attacks that could compromise the entire system. Organizations should implement immediate mitigations including applying security patches, monitoring for unauthorized permission usage, and ensuring proper access control enforcement within package management services to prevent exploitation of this critical flaw.