CVE-2021-0682 in Android
Summary
by MITRE • 10/06/2021
In sendAccessibilityEvent of NotificationManagerService.java, there is a possible disclosure of notification data due to a missing permission check. This could lead to local information disclosure with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-8.1 Android-9 Android-10Android ID: A-159624555
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Analysis
by VulDB Data Team • 10/10/2021
The vulnerability identified as CVE-2021-0682 resides within the Android notification system, specifically in the sendAccessibilityEvent method of the NotificationManagerService.java component. This flaw represents a critical security oversight that allows unauthorized access to sensitive notification data through a missing permission validation mechanism. The vulnerability affects multiple Android versions including Android 8.1, 9, 10, and 11, indicating a widespread impact across the Android ecosystem. The issue stems from insufficient access controls that fail to verify whether the requesting process has proper authorization to access notification information, creating a potential pathway for information disclosure.
The technical implementation flaw manifests in the NotificationManagerService's handling of accessibility events where the system fails to perform adequate permission verification before exposing notification data. This missing permission check creates a privilege escalation vector that can be exploited by malicious applications running with user-level privileges. The vulnerability operates at the system level within the Android framework, specifically targeting the notification management service that handles accessibility events. According to CWE-284, this represents an improper access control vulnerability where the system fails to enforce proper authorization checks. The flaw allows for local information disclosure because the notification data that should remain protected becomes accessible to any application that can trigger the specific accessibility event mechanism.
The operational impact of this vulnerability extends beyond simple data exposure, as notification data often contains sensitive information including personal messages, system alerts, and application-specific details that could be leveraged for further attacks. An attacker with user execution privileges can exploit this vulnerability without requiring user interaction, making it particularly dangerous as it can be triggered automatically. The local information disclosure threat means that malicious applications can access notification content that might contain credentials, personal communications, or system alerts that reveal sensitive operational details. This vulnerability aligns with ATT&CK technique T1056.001 which covers credential harvesting through input capture, as notification data often contains sensitive information that could be exploited for privilege escalation or identity theft.
The mitigation strategy for CVE-2021-0682 requires immediate implementation of proper permission validation within the NotificationManagerService component. Android security patches should enforce strict access controls that verify the calling application's permissions before allowing notification data exposure. System administrators and device manufacturers should prioritize applying the relevant security updates that address this permission check deficiency. Additionally, developers should implement robust input validation and access control mechanisms within their applications to prevent exploitation of similar vulnerabilities. The fix should include comprehensive permission verification that ensures only authorized processes can access notification data through accessibility events. Organizations should also consider implementing application sandboxing and runtime monitoring to detect potential exploitation attempts, as the vulnerability operates at the system framework level and may be difficult to detect through traditional security scanning methods.