CVE-2017-9994 in FFmpeg
Summary
by MITRE
libavcodec/webp.c in FFmpeg before 2.8.12, 3.0.x before 3.0.8, 3.1.x before 3.1.8, 3.2.x before 3.2.5, and 3.3.x before 3.3.1 does not ensure that pix_fmt is set, which allows remote attackers to cause a denial of service (heap-based buffer overflow and application crash) or possibly have unspecified other impact via a crafted file, related to the vp8_decode_mb_row_no_filter and pred8x8_128_dc_8_c functions.
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Analysis
by VulDB Data Team • 12/09/2022
The vulnerability identified as CVE-2017-9994 represents a critical heap-based buffer overflow in the FFmpeg multimedia framework's WebP decoder component. This flaw exists in multiple version ranges including 2.8.12, 3.0.8, 3.1.8, 3.2.5, and 3.3.1, making it a widespread issue affecting numerous implementations of the multimedia processing library. The vulnerability stems from insufficient validation of pixel format parameters within the WebP decoding process, specifically in the vp8_decode_mb_row_no_filter and pred8x8_128_dc_8_c functions. When processing maliciously crafted WebP files, the decoder fails to properly initialize or validate the pix_fmt parameter, creating conditions that lead to memory corruption. This vulnerability is particularly dangerous because it can be exploited remotely through crafted media files, allowing attackers to trigger denial of service conditions that result in application crashes or potentially more severe consequences. The heap-based buffer overflow occurs when the decoder attempts to write data beyond allocated memory boundaries, which can corrupt adjacent memory regions and cause unpredictable behavior.
The technical exploitation of this vulnerability requires an attacker to craft a specially formatted WebP file that triggers the flawed decoding path. The vulnerability maps to CWE-121 Heap-based Buffer Overflow, which specifically addresses buffer overflows occurring in heap memory regions. When the affected FFmpeg versions process such malicious files, the decoder's handling of the vp8_decode_mb_row_no_filter function fails to properly validate pixel format information, leading to memory corruption. The pred8x8_128_dc_8_c function, which is part of the VP8 video decoding process, becomes a critical execution point where the buffer overflow manifests. This vulnerability can be categorized under ATT&CK technique T1203, which involves exploiting software vulnerabilities to cause system instability. The impact extends beyond simple denial of service as the heap corruption could potentially be leveraged for more advanced exploitation techniques, though the primary documented impact remains application crash and system instability.
The operational impact of CVE-2017-9994 is significant for any system utilizing FFmpeg for media processing, particularly web applications, media servers, and content management systems. Organizations running vulnerable versions of FFmpeg are at risk of service disruption when processing user-uploaded media files or when exposed to malicious content from external sources. The vulnerability affects a broad range of applications including media streaming platforms, social media services, content delivery networks, and any software that relies on FFmpeg for video and image processing. The remote exploitability makes this particularly concerning for web-facing applications where users can upload media files without proper sanitization. Additionally, the vulnerability can impact enterprise media processing pipelines, digital asset management systems, and any infrastructure that automatically processes multimedia content. The potential for unspecified other impacts suggests that while the primary concern is denial of service, there may be additional security implications that could be exploited in combination with other vulnerabilities. Organizations should prioritize patching affected systems and implementing proper media file validation and sanitization measures to prevent exploitation of this vulnerability across their infrastructure.