CVE-2021-0995 in Android
Summary
by MITRE • 12/15/2021
In registerSuggestionConnectionStatusListener of WifiServiceImpl.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-197536547
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Analysis
by VulDB Data Team • 12/18/2021
The vulnerability identified as CVE-2021-0995 resides within the Android operating system's WifiServiceImpl.java component, specifically in the registerSuggestionConnectionStatusListener method. This flaw represents a significant information disclosure issue that exploits side channel information to determine application installation status without requiring explicit query permissions. The vulnerability affects Android 12 systems and is catalogued under Android ID A-197536547, demonstrating how seemingly innocuous system services can be leveraged for unauthorized reconnaissance activities.
The technical mechanism behind this vulnerability involves the improper handling of connection status listener registrations within the Wi-Fi service implementation. When applications register for suggestion connection status notifications, the system inadvertently exposes information about installed applications through timing variations or other side channel characteristics. This occurs because the system's response to registration requests differs based on whether target applications are installed, creating a distinguishable pattern that malicious actors can exploit to infer application presence. The flaw operates at the system service level where the Wi-Fi implementation should maintain strict isolation between different applications' privacy boundaries.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to perform application enumeration without requiring traditional permission grants or user interaction. An attacker can leverage this weakness to build comprehensive profiles of installed applications on a device, potentially identifying security-sensitive applications or those with known vulnerabilities. The lack of additional execution privileges required for exploitation makes this particularly concerning, as it can be exploited by any application with basic Wi-Fi connectivity permissions. This vulnerability directly relates to CWE-200, Information Exposure, and aligns with ATT&CK technique T1069.001 for Permission Groups and T1592.001 for Inventory of Systems.
Mitigation strategies for this vulnerability should focus on implementing proper access controls and ensuring that system services do not expose information about application state through side channels. Android security updates should include modifications to the WifiServiceImpl.java implementation to normalize response times and eliminate distinguishable patterns that could reveal application installation status. Device manufacturers should also consider implementing additional sandboxing measures for Wi-Fi service components and establishing stricter boundaries between different application contexts. The vulnerability underscores the importance of comprehensive security testing that considers side channel attacks and demonstrates how even minor implementation details in system services can create significant privacy and security risks.