CVE-2023-21337 in Android
Summary
by MITRE • 10/30/2023
In InputMethod, 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 escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 09/07/2024
The vulnerability identified as CVE-2023-21337 resides within the InputMethod component of Android systems, representing a significant information disclosure flaw that undermines the security model's integrity. This weakness allows attackers to perform unauthorized app enumeration through side channel analysis without requiring explicit query permissions or user interaction. The vulnerability operates at the system level where input method services interface with applications, creating an unintended information flow that reveals installed application presence. Such a flaw fundamentally compromises the principle of least privilege and application isolation that Android security relies upon for protecting user privacy and system integrity.
The technical implementation of this vulnerability stems from improper handling of input method service interactions where the system fails to adequately sanitize information flows between the input method and application components. When an input method service processes text input or interacts with application interfaces, it inadvertently exposes metadata about installed applications through timing variations, memory access patterns, or other observable side channel characteristics. This information leakage occurs even when the input method service does not possess explicit permissions to query installed applications, creating a covert channel that bypasses normal security controls. The flaw exists in the underlying system architecture where input method services maintain state information that can be inferred through careful analysis of system behavior patterns.
The operational impact of CVE-2023-21337 extends beyond simple information disclosure to enable potential local privilege escalation scenarios. Attackers can leverage this vulnerability to enumerate installed applications and subsequently target specific applications for more sophisticated attacks, including exploitation of application-specific vulnerabilities or targeted malware delivery. The lack of user interaction requirement makes this vulnerability particularly dangerous as it can be exploited automatically without any user awareness or consent. This capability enables automated reconnaissance phases where attackers can map application landscapes and identify high-value targets within the device. The vulnerability aligns with attack patterns described in the attack tree methodology where information disclosure serves as a foundational step for more complex exploitation techniques.
Mitigation strategies for this vulnerability require comprehensive system-level patches that address the underlying information flow issues within input method services. System administrators and device manufacturers must implement immediate security updates that modify how input method services handle application state information and prevent side channel leakage. The fix should involve strict isolation mechanisms that ensure input method services cannot infer installed application information through system behavior analysis. Additionally, implementing proper access controls and privilege separation between input method components and application enumeration functions will help prevent unauthorized information disclosure. This vulnerability demonstrates the importance of considering side channel attacks in security design and aligns with CWE-203, which addresses "Information Exposure Through Side Channels," and represents a significant concern for security frameworks that must account for covert information pathways in mobile operating systems.