CVE-2021-0978 in Android
Summary
by MITRE • 12/15/2021
In getSerialForPackage of DeviceIdentifiersPolicyService.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-192587406
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Analysis
by VulDB Data Team • 12/18/2021
This vulnerability exists within the Android operating system's DeviceIdentifiersPolicyService component and specifically affects the getSerialForPackage method in the DeviceIdentifiersPolicyService.java file. The flaw represents a side channel information disclosure vulnerability that allows malicious applications to determine whether other applications are installed on the device without requiring any special permissions or user interaction. The vulnerability stems from the way the system handles serial number generation and package identification, creating an information leakage channel that can be exploited by adversaries to infer application installation status.
The technical implementation of this vulnerability leverages timing differences or other observable characteristics in the system's response when processing package serial number requests. When an application attempts to query serial information for a package, the system's response behavior varies depending on whether the target package is installed or not. This differential response creates a timing side channel that can be analyzed to determine application presence. The vulnerability is classified under CWE-203: Information Exposure Through Timing Discrepancy, which specifically addresses information leakage caused by timing variations in system responses. This type of information disclosure can be particularly dangerous as it enables adversaries to build detailed profiles of installed applications on target devices without requiring explicit permissions.
The operational impact of this vulnerability is significant for user privacy and security. Attackers can use this information to construct comprehensive inventories of installed applications, potentially identifying sensitive applications, security tools, or enterprise software. This information can be combined with other reconnaissance techniques to create targeted attack vectors or to understand the security posture of individual devices. The vulnerability is particularly concerning because it requires no additional execution privileges or user interaction, making it extremely easy to exploit. The attack can be performed entirely within the application sandbox, and the information disclosure occurs silently in the background without any visible user prompts or system warnings.
The exploitation of this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1069.001 tactic for "Permission Groups Discovery" and T1592.004 for "Resource Hijacking." The lack of need for additional privileges means that even sandboxed applications can leverage this information to perform reconnaissance activities. The vulnerability affects Android 12 systems and represents a critical privacy concern since it enables passive monitoring of application installation status without user knowledge or consent. Organizations should consider this vulnerability when assessing their mobile security posture, particularly in environments where device privacy is paramount. The issue highlights the importance of proper input validation and response normalization in system components that handle sensitive information requests. Users should ensure their devices are updated with the latest security patches to mitigate this exposure, and security teams should monitor for potential exploitation patterns in their network traffic analysis.