CVE-2021-1012 in Android
Summary
by MITRE • 12/15/2021
In onResume of NotificationAccessDetails.java, there is a possible way to determine whether an app is installed, without query permissions, due to side channel information disclosure. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-195412179
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Analysis
by VulDB Data Team • 12/18/2021
This vulnerability exists within the Android notification access framework where the onResume method in NotificationAccessDetails.java inadvertently exposes information about installed applications through side channel mechanisms. The flaw allows malicious applications to determine the presence of other applications on a device without requiring explicit query permissions or user interaction. This represents a significant privacy and security concern as it enables unauthorized enumeration of installed applications through indirect information disclosure channels.
The technical implementation of this vulnerability stems from how the notification access service handles the onResume lifecycle event. When an application with notification access privileges resumes, the system's handling of notification data and access patterns creates observable side channel information that can be exploited to infer application installation status. This occurs because the system's internal state management during the onResume transition reveals information about which applications are registered for notification access or have active notification channels. The vulnerability operates at the framework level where notification access permissions are managed, creating a pathway for information leakage that bypasses normal permission boundaries.
From an operational perspective, this vulnerability enables local information disclosure attacks that can be executed without requiring additional privileges or user interaction. An attacker with notification access permissions can leverage this flaw to map the application landscape of a device, potentially identifying sensitive applications or applications with specific capabilities. The impact extends beyond simple application enumeration as it could enable more sophisticated attacks such as application fingerprinting, targeted phishing attempts, or exploitation of application-specific vulnerabilities. This type of information disclosure aligns with attack patterns documented in the attack tree where adversaries seek to understand the target environment before launching more complex operations.
The vulnerability manifests as a weakness in the Android permission model and information flow control mechanisms, specifically related to how notification access is implemented and how system resources are managed during application lifecycle transitions. It represents a deviation from the principle of least privilege where the system should not expose information beyond what is explicitly granted through permissions. The flaw demonstrates a failure in the security boundary enforcement between notification access and application enumeration, creating a covert channel for information leakage. This issue is particularly concerning as it operates without requiring user interaction and can be exploited by any application with notification access privileges.
Mitigation strategies should focus on implementing proper isolation between notification access functionality and application enumeration mechanisms. System-level patches should ensure that the onResume method and related notification access handlers do not expose information about installed applications through side channels. Developers should review notification access implementations to eliminate information leakage patterns and ensure that permission boundaries are properly enforced. The fix should address the root cause by preventing the disclosure of installation status information through notification access services, which aligns with security best practices outlined in the CWE catalog for information leakage vulnerabilities. Organizations should also consider monitoring for abnormal notification access patterns that might indicate exploitation attempts and implement proper application sandboxing to limit the impact of such vulnerabilities.