CVE-2018-13302 in FFmpeg
Summary
by MITRE
In FFmpeg 4.0.1, improper handling of frame types (other than EAC3_FRAME_TYPE_INDEPENDENT) that have multiple independent substreams in the handle_eac3 function in libavformat/movenc.c may trigger an out-of-array access while converting a crafted AVI file to MPEG4, leading to a denial of service or possibly unspecified other impact.
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Analysis
by VulDB Data Team • 04/03/2023
The vulnerability CVE-2018-13302 represents a critical buffer overflow condition within the FFmpeg multimedia framework version 4.0.1 that specifically affects the handling of EAC3 (Enhanced AC-3) audio streams during file format conversion operations. This issue resides in the movenc.c source file within the libavformat module, where the handle_eac3 function fails to properly validate frame type parameters when processing audio data containing multiple independent substreams. The flaw manifests when FFmpeg encounters an AVI file with EAC3 audio content that does not conform to the standard EAC3_FRAME_TYPE_INDEPENDENT frame type, creating a scenario where array bounds are exceeded during the conversion process to MPEG4 format.
The technical exploitation of this vulnerability stems from inadequate input validation mechanisms within the audio stream processing pipeline. When FFmpeg processes an EAC3 frame that contains multiple independent substreams but is not classified as EAC3_FRAME_TYPE_INDEPENDENT, the function attempts to access array elements beyond their allocated memory boundaries. This improper memory access occurs during the conversion workflow where the software attempts to map and encode audio substream data into the target MPEG4 container format. The vulnerability is classified under CWE-129 as an "Improper Validation of Array Index" and aligns with ATT&CK technique T1499.001 for "Network Denial of Service" through software exploitation.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more severe consequences depending on the execution environment. An attacker could craft a malicious AVI file containing specially formatted EAC3 audio streams to trigger the buffer overflow, causing the FFmpeg process to crash or terminate unexpectedly. In environments where FFmpeg is used as a backend service for media processing, this could result in complete service disruption and availability loss for legitimate users. The vulnerability's potential for unspecified other impacts suggests that under certain conditions, the out-of-bounds memory access might be exploitable for arbitrary code execution, particularly in contexts where the application runs with elevated privileges or where memory corruption could be leveraged for further attack vectors.
Mitigation strategies for this vulnerability require immediate patching of FFmpeg installations to versions that contain the corrected handling of EAC3 frame types and array boundary validation. System administrators should implement comprehensive media file validation processes that screen incoming audio content for malformed EAC3 streams before processing. The fix implemented in subsequent FFmpeg versions addresses the core issue by introducing proper bounds checking and frame type validation within the handle_eac3 function, ensuring that all array accesses are validated against the actual number of substreams present in the EAC3 frame. Organizations should also consider implementing sandboxed processing environments for media conversion tasks and employing automated security scanning tools to detect potentially malicious media files before they are processed by FFmpeg components.