CVE-2017-18247 in libav
Summary
by MITRE
The av_audio_fifo_size function in libavutil/audio_fifo.c in Libav 12.2 allows remote attackers to cause a denial of service (NULL pointer dereference) via a crafted media file.
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Analysis
by VulDB Data Team • 01/16/2020
The vulnerability identified as CVE-2017-18247 represents a critical denial of service flaw within the Libav multimedia framework, specifically affecting the av_audio_fifo_size function located in libavutil/audio_fifo.c. This issue manifests when processing crafted media files that exploit a NULL pointer dereference condition, potentially leading to application crashes and system instability. The vulnerability impacts Libav version 12.2 and demonstrates how improper input validation can create security risks in multimedia processing libraries that handle diverse media formats.
The technical implementation of this vulnerability stems from insufficient validation of audio fifo parameters during the processing of audio data streams. When a maliciously crafted media file is processed, the av_audio_fifo_size function fails to properly handle cases where audio fifo structures may be uninitialized or improperly allocated, resulting in a NULL pointer dereference. This flaw operates at the core level of audio processing within the Libav library, making it particularly dangerous as it can be triggered through normal media file parsing operations without requiring special privileges or complex attack vectors.
From an operational perspective, this vulnerability creates significant risks for systems that rely on Libav for media processing tasks including streaming services, multimedia applications, and content management systems. The denial of service impact means that legitimate users may experience service disruption when encountering malicious media files, potentially allowing attackers to perform sustained denial of service attacks against media processing services. The vulnerability affects the availability of multimedia processing capabilities and can be exploited across various networked systems that utilize Libav for audio handling operations.
Security practitioners should implement immediate mitigations including updating to patched versions of Libav where available, implementing input validation measures for media files, and deploying network segmentation to limit exposure to potentially malicious content. The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions, and demonstrates characteristics consistent with ATT&CK technique T1499.3 for denial of service attacks. Organizations should also consider implementing media file sanitization processes and monitoring for unusual processing patterns that might indicate exploitation attempts. The remediation approach should include comprehensive testing of media processing pipelines to ensure proper handling of edge cases and malformed input data.