CVE-2019-2139 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-117610049
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Analysis
by VulDB Data Team • 09/11/2020
The vulnerability identified as CVE-2019-2139 affects the libxaac library component within Android systems, specifically impacting Android 10 installations. This issue represents a critical out-of-bounds read condition that stems from insufficient input validation mechanisms within the audio processing framework. The flaw exists in the Advanced Audio Coding (AAC) decoding implementation where proper bounds checking has been omitted during buffer operations. The vulnerability manifests when processing specially crafted audio files that trigger memory access beyond allocated buffer boundaries. According to the Android security advisory A-117610049, this vulnerability requires user interaction for exploitation, meaning an attacker must convince a user to open or play a maliciously formatted audio file. The security implications are significant as this out-of-bounds read could potentially expose sensitive memory contents to unauthorized parties, leading to information disclosure attacks.
The technical implementation of this vulnerability resides in the libxaac library's handling of AAC audio data streams where memory buffers are not properly validated against the actual data size being processed. This missing bounds check creates an opportunity for attackers to manipulate audio file inputs to cause the decoder to read memory locations beyond the intended buffer limits. The flaw operates at the intersection of audio codec processing and memory management, where insufficient validation allows for data corruption and information leakage. The vulnerability aligns with CWE-129, which specifically addresses insufficient validation of length of inputs, and represents a classic example of improper input validation leading to memory safety issues. The attack vector requires user interaction through the exploitation of the audio processing pipeline, making it particularly concerning for mobile environments where users frequently interact with multimedia content.
The operational impact of CVE-2019-2139 extends beyond simple information disclosure, as it could potentially enable attackers to extract sensitive data from the device's memory space. This includes but is not limited to cryptographic keys, user credentials, or application data that might be stored in adjacent memory regions. The vulnerability's exploitation requires no additional privileges beyond normal user execution capabilities, making it particularly dangerous in mobile environments where applications have broad access to device resources. Attackers could leverage this vulnerability to gain insights into the device's internal state, potentially aiding in more sophisticated attacks such as privilege escalation or targeted data exfiltration. The attack surface is particularly relevant in Android environments where the libxaac library is frequently used for audio processing in both system applications and third-party media players, creating multiple potential entry points for exploitation.
Mitigation strategies for CVE-2019-2139 should prioritize the immediate deployment of Android security patches that address the bounds checking deficiency in libxaac. System administrators and device manufacturers must ensure that all affected Android 10 devices receive the appropriate updates to remediate this vulnerability. Additional protective measures include implementing strict input validation for audio file processing, deploying network-level monitoring to detect anomalous audio processing patterns, and establishing secure coding practices that emphasize bounds checking in memory-intensive operations. Organizations should also consider implementing application whitelisting to restrict the execution of untrusted audio processing applications and maintain regular security assessments of multimedia processing components. The vulnerability serves as a reminder of the importance of robust memory safety mechanisms in multimedia libraries and the critical need for comprehensive input validation in audio codec implementations. This case study aligns with ATT&CK technique T1059.007 for audio processing and demonstrates how seemingly benign multimedia operations can become attack vectors when proper security controls are lacking.