CVE-2019-9321 in Android
Summary
by MITRE
In libavc, there is a missing variable initialization. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-111208713
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Analysis
by VulDB Data Team • 09/12/2020
The vulnerability identified as CVE-2019-9321 affects the libavc library component within Android systems, specifically impacting Android 10 deployments. This issue stems from a critical missing variable initialization flaw that creates potential security risks for remote information disclosure attacks. The vulnerability resides in the video decoding library responsible for processing AVC (Advanced Video Coding) format content, which is widely used in multimedia applications and system components. The flaw represents a classic software development oversight where a variable intended for security purposes fails to be properly initialized before use, creating unpredictable behavior that adversaries can potentially exploit. The Android security team assigned this vulnerability with identifier A-111208713, highlighting its significance within the Android ecosystem and the need for prompt remediation.
The technical implementation of this vulnerability involves a specific code path within the libavc library where a variable intended to control access or store security-sensitive information remains uninitialized during the video processing routine. When the system processes AVC formatted video content, this uninitialized variable can contain residual data from previous operations or memory contents that were not properly cleared. This uninitialized state creates a potential information leak channel where attackers can potentially extract sensitive data through carefully crafted video content or network streams. The vulnerability requires user interaction for exploitation, meaning that a malicious actor would need to convince a user to open or process specific media content that triggers the vulnerable code path. The attack vector typically involves specially crafted video files or network streams that cause the system to execute the problematic code sequence, leading to the information disclosure through the uninitialized variable behavior.
The operational impact of CVE-2019-9321 extends beyond simple information disclosure, as it represents a fundamental security weakness in the Android multimedia processing pipeline that could potentially be leveraged for more sophisticated attacks. The vulnerability's classification as a remote information disclosure means that adversaries could potentially extract sensitive data without requiring local system access or elevated privileges, making it particularly concerning for mobile environments where users frequently process content from untrusted sources. The lack of additional execution privileges needed for exploitation reduces the attack complexity and increases the likelihood of successful exploitation. This vulnerability aligns with CWE-457, which describes the use of uninitialized variables, a category that frequently leads to unpredictable behavior and security vulnerabilities in software systems. The impact is particularly severe in mobile environments where multimedia processing is common and users may unknowingly encounter malicious content through various channels including messaging applications, web browsing, or media sharing platforms.
Mitigation strategies for CVE-2019-9321 should prioritize the immediate deployment of Android security patches that address the uninitialized variable issue within the libavc library. System administrators and device manufacturers should ensure that all Android 10 devices receive the appropriate updates that properly initialize the affected variables before use. The recommended approach includes implementing comprehensive code review processes to identify similar uninitialized variable issues in other system components and applying consistent initialization patterns throughout the multimedia processing pipeline. Security monitoring should focus on detecting unusual video processing patterns or unexpected memory access behaviors that might indicate exploitation attempts. Organizations should also consider implementing network-based filtering mechanisms to block or scan suspicious video content before it reaches end-user devices. The vulnerability demonstrates the importance of adhering to secure coding practices and proper initialization protocols, particularly in security-sensitive components. This issue relates to ATT&CK technique T1059.007 for command and scripting interpreter, as attackers may leverage information disclosure to gather intelligence for subsequent attack phases, and T1068 for exploit for privilege escalation, since the initial information leak could enable more sophisticated attacks. The vulnerability underscores the necessity of comprehensive security testing including static analysis and dynamic testing of multimedia processing components to identify similar initialization flaws before they can be exploited in real-world scenarios.