CVE-2019-9336 in Android
Summary
by MITRE
In libavc there is a possible information disclosure due to uninitialized data. 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-112326322
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Analysis
by VulDB Data Team • 09/12/2020
The vulnerability identified as CVE-2019-9336 resides within the libavc component of Android systems, specifically affecting Android 10 deployments. This issue represents a classic case of uninitialized memory access that can potentially expose sensitive information to unauthorized parties. The flaw manifests in the way the system handles certain data structures within the video codec processing pipeline, creating an avenue for information disclosure attacks.
The technical root cause of this vulnerability stems from the improper initialization of memory buffers within the libavc library implementation. When processing video streams, the system fails to properly initialize certain data structures before use, leading to the potential exposure of previously allocated memory contents that may contain sensitive information from other processes or system components. This uninitialized data exposure creates a scenario where attackers can potentially extract confidential information through carefully crafted video content. The vulnerability operates at the system level within the multimedia framework, specifically affecting the Advanced Video Coding implementation that handles video decoding and processing operations.
From an operational perspective, this vulnerability presents a significant risk as it enables remote information disclosure without requiring any additional privileges beyond what is normally available to users. The attack vector requires user interaction to be successful, meaning that a malicious actor would need to convince a victim to open or process a specially crafted video file or stream. This interaction requirement makes the attack more challenging to execute at scale but does not eliminate the threat entirely. The impact extends beyond simple information disclosure, as the exposed data could potentially contain credentials, cryptographic keys, or other sensitive system information that could be leveraged for further attacks. This vulnerability aligns with CWE-457, which describes the use of uninitialized variables, and represents a clear violation of secure coding practices in the Android multimedia subsystem.
The exploitation of this vulnerability requires an attacker to craft malicious video content that triggers the specific code path containing the uninitialized data issue. The attack process typically involves sending a specially formatted video file to a target device, which then processes the content through the vulnerable libavc library. When the system attempts to decode or process the malicious video, the uninitialized memory access occurs, potentially exposing sensitive information from the device's memory space. This attack pattern fits within the ATT&CK framework under the T1059.007 technique for "Command and Scripting Interpreter: JavaScript" and T1566.001 for "Phishing: Spearphishing Attachment", as it relies on social engineering to deliver malicious content to vulnerable systems.
Mitigation strategies for CVE-2019-9336 primarily involve applying the relevant security patches provided by Google and device manufacturers. The Android Security Bulletin for the affected period included fixes that properly initialize the memory structures within the libavc library, preventing the exposure of uninitialized data. Organizations should ensure that all Android devices are updated to the latest security patches, particularly those addressing the October 2019 security updates. Additionally, network administrators should implement content filtering measures to prevent the delivery of potentially malicious video content to devices. The vulnerability highlights the importance of secure coding practices, particularly regarding memory initialization and proper input validation in multimedia processing libraries. System monitoring should include detection of unusual video processing activities that might indicate exploitation attempts. This vulnerability serves as a reminder of the critical importance of proper memory management in system libraries and the potential consequences of failing to initialize data structures appropriately, particularly in components that handle user-supplied content.