CVE-2019-2138 in Android
Summary
by MITRE
In libxaac, there is a possible out of bounds read due to a missing bounds check. This could lead to information disclosure with no additional execution privileges needed. User interaction is needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-118494320
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Analysis
by VulDB Data Team • 09/11/2020
The vulnerability identified as CVE-2019-2138 resides within the libxaac library component of Android systems, specifically affecting Android 10 implementations. This issue represents a classic out-of-bounds read condition that occurs when the system fails to properly validate input data boundaries before processing audio content. The flaw manifests in the Advanced Audio Coding (AAC) decoding functionality where the application does not perform adequate bounds checking on audio frame data, creating a potential pathway for unauthorized data access.
This vulnerability falls under the CWE-129 category of Improper Validation of Array Index, which directly relates to the missing bounds check that allows the system to read memory locations beyond the intended buffer boundaries. The technical implementation flaw occurs during the parsing of AAC audio streams where the decoder assumes valid input parameters without proper validation, enabling maliciously crafted audio files to trigger memory access violations that can expose sensitive information from adjacent memory regions.
The operational impact of this vulnerability extends beyond simple information disclosure as it represents a significant security risk within mobile audio processing systems. Attackers can exploit this weakness by crafting specially formatted audio files that, when processed by the vulnerable libxaac library, cause the system to read beyond allocated memory boundaries. The requirement for user interaction means that exploitation typically occurs through social engineering tactics where users are tricked into playing malicious audio content, making the attack vector more plausible in real-world scenarios. The lack of additional execution privileges required for exploitation lowers the barrier for successful attacks, as the vulnerability can be leveraged through standard user-level operations.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1068 which describes the use of legitimate credentials and privileges to gain access to system resources. The attack chain involves initial user interaction with malicious content followed by exploitation of the audio processing pipeline to extract sensitive data. The vulnerability demonstrates how multimedia processing libraries can become attack surfaces where seemingly benign input processing can lead to information disclosure. Mitigation strategies should focus on implementing comprehensive input validation, adding robust bounds checking mechanisms, and applying timely security patches to the Android system components. Additionally, organizations should consider implementing audio file validation procedures and monitoring for unusual audio processing patterns that might indicate exploitation attempts.
The Android security model's reliance on proper input validation becomes particularly critical in this scenario, as the vulnerability exists within a core system component responsible for processing user media content. The vulnerability's classification as information disclosure rather than arbitrary code execution means that attackers cannot directly execute malicious code but can still extract sensitive data from system memory. This makes the vulnerability particularly concerning for environments where Android devices handle confidential information or operate in security-sensitive contexts where information exposure could lead to broader compromise. The vulnerability serves as a reminder of the importance of thorough input validation in all system components, especially those processing user-supplied media content that may be manipulated to exploit underlying implementation flaws.