CVE-2021-1015 in Android
Summary
by MITRE • 12/15/2021
In getMeidForSlot of PhoneInterfaceManager.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-186530496
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Analysis
by VulDB Data Team • 12/22/2021
This vulnerability exists in the Android operating system's telephony subsystem, specifically within the PhoneInterfaceManager.java component that manages phone interface functionality. The flaw resides in the getMeidForSlot method which is designed to retrieve the Mobile Equipment Identifier for specific phone slots. The vulnerability stems from improper handling of information disclosure through side channel mechanisms that inadvertently reveal whether applications are installed on the device. This represents a significant privacy and security concern as it allows unauthorized information gathering without requiring any special permissions or user interaction. The vulnerability has been classified with a high severity rating due to its potential for local information disclosure and the minimal attack surface required for exploitation.
The technical implementation of this vulnerability involves the PhoneInterfaceManager component exposing timing or behavioral differences in its response handling when processing requests for MEID information across different phone slots. When an application attempts to query MEID information for a slot that contains an installed application versus one that does not, the system exhibits measurable differences in processing time or response patterns that can be exploited by malicious applications. This side channel information leakage occurs because the system does not properly normalize its response behavior regardless of whether the target slot contains an installed application or not. The vulnerability specifically affects Android 12 systems and has been assigned the Android ID A-186530496, indicating it was discovered and tracked within Google's internal vulnerability tracking system. The flaw operates at the system level within the telephony framework, making it particularly concerning as it bypasses traditional permission-based security models.
The operational impact of this vulnerability extends beyond simple information disclosure as it enables sophisticated reconnaissance attacks that can map application installations on target devices. Attackers can leverage this weakness to build detailed profiles of installed applications without requiring explicit permissions, which could then be used to tailor more targeted attacks or exploit known vulnerabilities in specific applications. The lack of user interaction requirement means this vulnerability can be exploited automatically by malware or malicious applications running in the background. This type of information leakage could be particularly damaging in enterprise environments where device security is paramount, as it could reveal sensitive application inventories that might contain proprietary or confidential software. The vulnerability also demonstrates a broader concern with side channel attacks in mobile operating systems where system-level components may inadvertently expose information through timing variations or resource access patterns.
Mitigation strategies for this vulnerability should focus on implementing proper response normalization within the PhoneInterfaceManager component to ensure consistent processing behavior regardless of slot content. System updates and patches should address the underlying implementation flaw by ensuring that MEID queries return consistent timing characteristics and response patterns. Organizations should also consider implementing additional monitoring for unusual telephony API usage patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-203 (Information Exposure Through Discrepancy) and represents a specific instance of side channel information leakage that could be addressed through proper cryptographic timing constant implementations. Security teams should review their mobile device management policies to ensure that Android systems are kept up to date with security patches and consider implementing additional application sandboxing measures to limit the potential impact of such vulnerabilities. This type of vulnerability also highlights the importance of comprehensive security testing of system-level APIs to identify potential side channel attack vectors that could be exploited by adversaries.