CVE-2018-19129 in libav
Summary
by MITRE
In Libav 12.3, a NULL pointer dereference (RIP points to zero) issue in ff_mpa_synth_filter_float in libavcodec/mpegaudiodsp_template.c can cause a segmentation fault (application crash) via a crafted mov file.
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Analysis
by VulDB Data Team • 04/11/2020
The vulnerability identified as CVE-2018-19129 represents a critical null pointer dereference flaw within the Libav multimedia framework version 12.3. This issue specifically affects the ff_mpa_synth_filter_float function located in the libavcodec/mpegaudiodsp_template.c source file. The vulnerability manifests when processing maliciously crafted mov files, which are commonly used multimedia container formats that can contain audio and video streams. The flaw occurs during the MPEG audio synthesis filtering process where the application attempts to dereference a null pointer, causing the register instruction pointer to point to address zero and resulting in a segmentation fault.
The technical nature of this vulnerability aligns with CWE-476, which specifically addresses null pointer dereference conditions in software systems. This flaw demonstrates how multimedia processing libraries can be exploited through carefully constructed input files that trigger unexpected memory access patterns. When a malicious mov file is processed by Libav, the ffmpeg or avconv command-line tools that utilize this library will encounter the null pointer dereference during audio synthesis operations, leading to immediate application termination. The vulnerability is particularly dangerous because it can be exploited remotely through web-based media processing, making it a significant concern for web applications and content management systems that process user-uploaded media files.
From an operational perspective, this vulnerability creates substantial risk for organizations that rely on Libav for media processing tasks, including content delivery networks, media streaming services, and web applications that handle multimedia uploads. The segmentation fault resulting from this null pointer dereference constitutes a denial-of-service condition that can be easily exploited to crash applications, potentially disrupting services and creating availability issues. Attackers can craft specific mov files that will trigger the vulnerability when processed by any application using the affected Libav version, making this a particularly attractive target for malicious actors seeking to disrupt services or establish persistent access through application crashes that could be leveraged in broader attack vectors.
The recommended mitigation strategies for CVE-2018-19129 involve immediate patching of the Libav library to version 12.4 or later, which contains the necessary fixes to prevent the null pointer dereference condition. Organizations should also implement input validation measures that filter or reject suspicious mov files before processing, particularly in web applications where user-uploaded content is common. Additionally, deploying intrusion detection systems that can identify and block attempts to exploit this specific vulnerability pattern would provide an additional layer of protection. The ATT&CK framework categorizes this type of vulnerability under the T1203 technique for "Exploitation for Client Execution" and T1499.004 for "Endpoint Denial of Service" as it enables attackers to cause application crashes through crafted input files, potentially leading to service disruption and system availability issues that align with the broader category of denial-of-service attacks targeting application-level vulnerabilities.