CVE-2018-9531 in Android
Summary
by MITRE
In AudioSpecificConfig_Parse of tpdec_asc.cpp, there is a possible out-of-bounds write due to a missing bounds check. This could lead to remote code execution with no additional execution privileges needed. User interaction is needed for exploitation. Product: Android. Versions: Android-9. Android ID: A-112661641
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Analysis
by VulDB Data Team • 04/13/2020
The vulnerability identified as CVE-2018-9531 represents a critical out-of-bounds write flaw within the AudioSpecificConfig_Parse function of the tpdec_asc.cpp file within Android's audio processing subsystem. This issue resides in the Advanced Audio Coding (AAC) decoder component that handles audio configuration data during media playback operations. The flaw manifests when parsing Audio Specific Configuration structures which are essential for proper audio decoding and playback of various media formats including mp4, aac, and other container formats that utilize AAC audio codecs.
The technical root cause stems from insufficient bounds checking within the AudioSpecificConfig_Parse function where the application fails to validate the size or length of incoming audio configuration data before attempting to write to memory locations. This missing validation allows an attacker to craft malicious audio files with malformed Audio Specific Configuration data that exceeds expected buffer boundaries. When the decoder processes such crafted input, it writes data beyond the allocated memory space, potentially overwriting adjacent memory regions including function pointers, return addresses, or other critical program data structures.
This vulnerability presents a significant remote code execution risk as it can be exploited through crafted media files delivered via email attachments, malicious websites, or compromised media streaming services. The attack requires only user interaction to open or play the malicious media file, making it particularly dangerous in real-world scenarios where users frequently encounter multimedia content. The exploitation process typically involves preparing an audio file with specifically crafted AAC configuration data that triggers the out-of-bounds write condition, potentially allowing an attacker to execute arbitrary code with the privileges of the media processing application.
The operational impact of CVE-2018-9531 extends beyond simple code execution as it affects Android devices running version 9.0 and potentially earlier versions where the vulnerable code remains present. The vulnerability affects the core media processing capabilities of Android, making it difficult to mitigate without system-wide updates. The attack vector through user interaction aligns with the ATT&CK framework's T1203 technique for legitimate credentials and T1059 for command and scripting interpreter, as the exploitation chain involves user behavior and system-level code execution. From a CWE perspective, this vulnerability maps to CWE-787 Out-of-bounds Write, which is a well-documented weakness in software systems where programs write data beyond the boundaries of allocated buffers.
Security mitigations for this vulnerability primarily involve applying the official Android security patches released by Google, which include bounds checking modifications to the AudioSpecificConfig_Parse function. Organizations should implement immediate patch management procedures to update all affected Android devices to the latest security releases. Additionally, network administrators should consider implementing media content filtering mechanisms to prevent the delivery of potentially malicious audio files through corporate networks. The vulnerability demonstrates the importance of proper input validation in multimedia processing libraries and highlights the need for robust memory safety practices in audio codec implementations. System administrators should also consider monitoring for unusual media processing activities that might indicate exploitation attempts, and maintain comprehensive backup and recovery procedures for affected devices.