CVE-2021-1020 in Android
Summary
by MITRE • 12/15/2021
In snoozeNotification of NotificationListenerService.java, there is a possible way to disable notification for an arbitrary user due to improper input validation. This could lead to local escalation of privilege with User execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-195111725
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 12/22/2021
The vulnerability identified as CVE-2021-1020 resides within the Android NotificationListenerService implementation, specifically in the snoozeNotification method of NotificationListenerService.java. This flaw represents a critical security weakness that allows unauthorized modification of notification behaviors, potentially enabling malicious actors to manipulate notification delivery mechanisms. The vulnerability stems from inadequate input validation within the notification management system, creating a pathway for privilege escalation attacks. The issue affects Android 12 systems and is tracked under Android ID A-195111725, highlighting its significance within the Android security framework.
The technical flaw manifests through improper validation of user inputs when processing notification snooze operations. When the snoozeNotification method processes incoming parameters, it fails to adequately verify the authenticity and legitimacy of the notification identifiers or user contexts being manipulated. This lack of proper input sanitization creates a condition where an attacker can craft malicious inputs that bypass normal access controls. The vulnerability operates at the system level where notification services interact with user permissions, allowing an attacker with user-level execution privileges to manipulate notification delivery for arbitrary users on the device. This represents a classic case of insufficient validation leading to privilege escalation, where the system's trust model is violated through malformed input processing.
The operational impact of this vulnerability extends beyond simple notification manipulation to represent a potential pathway for broader system compromise. An attacker could leverage this flaw to disable critical notifications for specific users, potentially hiding malicious activities or preventing users from receiving important security alerts. The requirement for user execution privileges means that exploitation typically requires initial access through social engineering, phishing, or other attack vectors that gain user-level access. However, once achieved, the privilege escalation capability allows for more significant control over notification systems, which could be used to disrupt service availability, hide malicious activities, or manipulate user experiences. The vulnerability affects the fundamental notification delivery mechanism that Android systems rely upon for security alerts, system updates, and user communications.
Mitigation strategies for CVE-2021-1020 should focus on implementing robust input validation and access control mechanisms within notification service components. Android security updates typically address such vulnerabilities through patches that strengthen parameter validation in notification processing methods. Organizations should ensure timely deployment of security patches and maintain awareness of notification service behavior changes. The vulnerability aligns with CWE-20, which describes improper input validation as a common weakness leading to various security issues. From an ATT&CK perspective, this vulnerability could be categorized under privilege escalation techniques where adversaries leverage system service weaknesses to gain elevated privileges. Security teams should monitor notification service logs for anomalous behavior and implement additional controls around notification management to prevent unauthorized manipulation of system alerts. The remediation process typically involves strengthening the input validation mechanisms in NotificationListenerService.java and ensuring proper user context validation during notification processing operations.