CVE-2021-0653 in Android
Summary
by MITRE • 12/15/2021
In enqueueNotification of NetworkPolicyManagerService.java, there is a possible way to retrieve a trackable identifier due to a missing permission check. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-9Android ID: A-177931370
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Analysis
by VulDB Data Team • 12/16/2021
The vulnerability identified in the NetworkPolicyManagerService.java file represents a critical permission enforcement flaw that allows unauthorized information disclosure through the enqueueNotification method. This issue affects Android versions 9, 10, and 11, demonstrating a persistent security weakness in the system's notification handling mechanisms. The root cause stems from a missing permission check within the notification queuing process, which creates an exploitable pathway for retrieving trackable identifiers without requiring any additional privileges or user interaction.
The technical implementation flaw occurs when the enqueueNotification method fails to validate whether the calling process possesses appropriate permissions before exposing sensitive tracking information. This absence of proper authorization checks creates a direct information disclosure vector where malicious applications can access identifiers that should remain protected within the system's security boundaries. The vulnerability operates at the system service level, specifically targeting the network policy management component that handles notification routing and processing.
From an operational impact perspective, this vulnerability enables local information disclosure attacks that can be exploited by any application running on the device without requiring elevated privileges or user interaction. The trackable identifiers retrieved through this method could include unique device identifiers, session tokens, or other sensitive metadata that could be used for fingerprinting, tracking, or further exploitation attempts. This creates a significant risk for user privacy and device security, as attackers can gather identifying information without needing to compromise additional system components.
The vulnerability aligns with CWE-284 which addresses improper access control issues in software systems. From an ATT&CK framework perspective, this represents a technique for privilege escalation and information gathering through local system service manipulation. The lack of user interaction requirements makes it particularly dangerous as it can be exploited silently during normal device operation without any warning to the user.
Mitigation strategies should focus on implementing proper permission validation within the enqueueNotification method and ensuring that all system services enforce appropriate access controls before exposing sensitive information. Device manufacturers should prioritize updating affected Android versions with patches that introduce mandatory permission checks for notification handling processes. Additionally, security researchers and developers should implement comprehensive logging of suspicious permission attempts to detect potential exploitation attempts. The fix requires modifications to the NetworkPolicyManagerService to validate calling process permissions before allowing access to tracking identifiers, ensuring compliance with Android's security model and protecting user privacy through proper authorization enforcement mechanisms.