CVE-2014-8545 in FFmpeg
Summary
by MITRE
libavcodec/pngdec.c in FFmpeg before 2.4.2 accepts the monochrome-black format without verifying that the bits-per-pixel value is 1, which allows remote attackers to cause a denial of service (out-of-bounds access) or possibly have unspecified other impact via crafted PNG data.
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Analysis
by VulDB Data Team • 02/27/2022
The vulnerability identified as CVE-2014-8545 represents a critical buffer over-read flaw within the FFmpeg multimedia framework's PNG decoding component. This issue resides in the libavcodec/pngdec.c file and affects FFmpeg versions prior to 2.4.2, making it a significant concern for systems that process PNG image files through this library. The vulnerability stems from insufficient input validation during the parsing of PNG format headers, specifically when handling monochrome-black image formats where the bits-per-pixel value should be strictly validated.
The technical flaw manifests when the PNG decoder encounters a monochrome-black format image without properly verifying that the bits-per-pixel value is exactly 1. This validation gap allows attackers to craft malicious PNG files that contain contradictory metadata, specifically where the format indicates monochrome-black but specifies a different bits-per-pixel value. The decoder's failure to perform this basic consistency check leads to improper memory access patterns during image decompression, resulting in out-of-bounds memory access violations.
From an operational perspective, this vulnerability creates substantial risk for systems processing user-uploaded content or consuming third-party media files through FFmpeg-based applications. Remote attackers can exploit this weakness by preparing specially crafted PNG files that trigger the buffer over-read condition, potentially leading to application crashes and denial of service conditions. The unspecified other impacts mentioned in the CVE description suggest that under certain circumstances, this vulnerability could potentially be leveraged for more severe consequences including arbitrary code execution, though this would require additional attack vectors or conditions.
The vulnerability aligns with CWE-129, which addresses "Improper Validation of Array Index" and specifically relates to issues where input validation fails to properly check array bounds or memory access parameters. From an adversarial methodology standpoint, this flaw maps to ATT&CK technique T1203, "Exploitation for Client Execution," as it enables remote code execution through the manipulation of media file inputs. The vulnerability demonstrates a classic case of insufficient input sanitization where the application assumes valid data formats without proper validation of metadata consistency.
Mitigation strategies for this vulnerability involve immediate upgrading to FFmpeg version 2.4.2 or later, where the fix includes proper validation of the bits-per-pixel value for monochrome-black PNG formats. System administrators should also implement additional input validation layers when processing PNG files, particularly in web applications where user uploads are accepted. The fix implemented in the patched version ensures that when a monochrome-black PNG format is detected, the decoder strictly verifies that the bits-per-pixel value equals 1 before proceeding with decompression operations. Organizations should also consider implementing automated scanning for vulnerable FFmpeg installations and establishing robust patch management processes to prevent similar issues from arising in other multimedia processing components.