CVE-2018-9550 in Android
Summary
by MITRE
In CAacDecoder_Init of aacdecoder.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-112660981.
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Analysis
by VulDB Data Team • 04/18/2020
The vulnerability identified as CVE-2018-9550 represents a critical out-of-bounds write flaw in the Advanced Audio Coding (AAC) audio decoding component of Android systems. This issue exists within the CAacDecoder_Init function located in the aacdecoder.cpp source file, where insufficient input validation allows maliciously crafted audio data to trigger memory corruption. The vulnerability specifically affects Android 9.0 systems and is tracked under Android ID A-112660981, demonstrating the severity of audio processing flaws in mobile operating systems where user interaction is required for exploitation.
The technical implementation of this vulnerability stems from a fundamental failure in bounds checking during the initialization phase of AAC audio decoding. When the decoder processes malformed audio streams, the missing validation allows an attacker to write data beyond the allocated memory boundaries of the decoder's internal buffers. This memory corruption directly maps to a potential remote code execution vector as described in CWE-121, which categorizes heap-based buffer overflow conditions. The flaw's exploitation requires user interaction, typically through the playback of malicious audio files, making it particularly concerning in mobile environments where users frequently encounter multimedia content.
The operational impact of CVE-2018-9550 extends beyond simple audio processing failures to represent a significant security risk in mobile device ecosystems. Attackers could leverage this vulnerability to execute arbitrary code on targeted devices without requiring elevated privileges, effectively bypassing standard Android security controls. The remote code execution capability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the exploitation would likely involve injecting malicious code through audio processing pathways. This vulnerability particularly impacts Android 9.0 systems where the media framework handles audio decoding, potentially affecting millions of devices through various applications that process audio content.
Mitigation strategies for this vulnerability require immediate system updates and patch management protocols. Android users should ensure their devices receive the latest security updates from their device manufacturers, as Google released patches addressing this specific memory corruption issue. System administrators should implement proactive monitoring for audio processing components and consider network-level filtering of suspicious audio content. The vulnerability's classification under CWE-787 for out-of-bounds write indicates that defensive programming practices including bounds checking, array size validation, and memory safety mechanisms should be enforced throughout the audio processing pipeline. Additionally, device manufacturers should implement runtime protections such as stack canaries and address space layout randomization to reduce exploitability even if the underlying vulnerability persists.