CVE-2021-39744 in Android
Summary
by MITRE • 03/30/2022
In DevicePolicyManager, 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-12LAndroid ID: A-192369136
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Analysis
by VulDB Data Team • 04/02/2022
This vulnerability resides within the Android DevicePolicyManager component, specifically exploiting a side channel information disclosure mechanism that allows unauthorized determination of application installation status. The flaw exists in Android 12L and represents a significant privacy and security concern as it enables information leakage without requiring any special permissions or execution privileges. The vulnerability stems from the device policy manager's handling of certain API calls that inadvertently expose information about installed applications through indirect means.
The technical implementation of this vulnerability involves the DevicePolicyManager's response to specific queries that should not reveal installation status information. When applications interact with device policy APIs, certain side channel behaviors occur that leak information about the presence or absence of other applications on the device. This occurs because the system's response timing, memory access patterns, or other indirect indicators vary based on whether target applications are installed, creating a covert channel for information extraction. The vulnerability operates at the system level where application enumeration should remain hidden from unauthorized accessors.
From an operational perspective, this vulnerability creates a pathway for local information disclosure that could be exploited by malicious applications or processes running with standard user privileges. Attackers could leverage this to build comprehensive profiles of devices, identifying installed applications and potentially correlating this information with known application vulnerabilities or behaviors. The lack of requirement for user interaction or additional execution privileges makes this particularly concerning as it can be exploited automatically without detection. The vulnerability's impact extends beyond simple enumeration to potentially enable more sophisticated attacks that rely on knowledge of installed applications.
The security implications of this vulnerability align with CWE-203, Information Exposure Through Side Channels, and can be mapped to ATT&CK technique T1083, File and Directory Discovery, as it enables unauthorized discovery of application installations. The flaw represents a failure in access control mechanisms within the Android framework where the system should maintain strict isolation between application installation information and unauthorized accessors. Mitigation strategies should include implementing proper access controls within the DevicePolicyManager, ensuring that API responses do not vary based on application installation status, and potentially introducing timing randomization or other anti-side-channel measures to prevent information leakage. The vulnerability underscores the importance of secure API design principles and the need for comprehensive security testing of system-level components that handle sensitive information exposure scenarios.