CVE-2021-1009 in Android
Summary
by MITRE • 12/15/2021
In setApplicationCategoryHint of PackageManagerService.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-189858128
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 12/18/2021
This vulnerability exists in the Android package manager service where the setApplicationCategoryHint method inadvertently exposes information about installed applications through side channel mechanisms. The flaw allows an attacker to determine whether a specific application is installed on the device without requiring any special permissions or query capabilities, effectively creating an information disclosure channel that bypasses normal security controls. The vulnerability stems from the way the system handles application category hints and how it processes information about installed packages, creating a timing or behavioral pattern that can be observed by malicious applications. This type of information disclosure represents a significant privacy risk as it enables adversaries to build profiles of installed applications without explicit user consent or permission grants.
The technical implementation of this vulnerability occurs within the PackageManagerService.java file where the setApplicationCategoryHint function processes application category information. The flaw manifests when the system's response time or memory access patterns vary depending on whether an application is installed or not, creating a side channel that can be exploited through careful observation of system behavior. This vulnerability specifically affects Android 12 systems and is identified by Android ID A-189858128, indicating it was discovered and tracked within Google's internal vulnerability management system. The issue does not require any user interaction or additional execution privileges, making it particularly concerning as it can be exploited by any application running on the device without needing to escalate privileges or obtain special permissions.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with valuable intelligence about the target device's application landscape. An adversary could use this information to tailor more sophisticated attacks, identify potential targets for further exploitation, or build comprehensive profiles of device users' application usage patterns. The vulnerability creates a persistent information leak that could be leveraged in combination with other techniques to establish more comprehensive surveillance capabilities. From a security perspective, this represents a failure in the principle of least privilege as the system exposes information that should remain private to the package manager service. The vulnerability aligns with CWE-200 (Information Exposure) and could be categorized under ATT&CK technique T1083 (File and Directory Discovery) when used for reconnaissance purposes.
Mitigation strategies for this vulnerability should focus on strengthening the package manager's handling of application category hints to eliminate the side channel information leak. System updates should ensure that the setApplicationCategoryHint method does not expose different behaviors based on application installation status. Developers should implement consistent response patterns regardless of whether applications are installed, eliminating timing variations that could be exploited. Organizations should also consider implementing runtime monitoring to detect unusual patterns that might indicate exploitation attempts. The vulnerability highlights the importance of considering side channel attacks in security design and emphasizes the need for comprehensive security testing that includes analysis of timing and behavioral patterns. Regular security audits of system services should be conducted to identify similar information disclosure vulnerabilities that could compromise user privacy and system integrity.