CVE-2013-2496 in FFmpeg
Summary
by MITRE
The msrle_decode_8_16_24_32 function in msrledec.c in libavcodec in FFmpeg through 1.1.3 does not properly determine certain end pointers, which allows remote attackers to cause a denial of service (out-of-bounds array access and application crash) or possibly have unspecified other impact via crafted Microsoft RLE data.
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Analysis
by VulDB Data Team • 05/06/2021
The vulnerability identified as CVE-2013-2496 resides within the FFmpeg multimedia framework's libavcodec library, specifically in the msrle_decode_8_16_24_32 function located in msrledec.c. This flaw represents a classic buffer boundary violation issue that occurs during the decoding process of Microsoft RLE (Run-Length Encoded) video data. The vulnerability affects FFmpeg versions through 1.1.3, making it a significant concern for systems that process multimedia content using this library. The issue stems from improper handling of end pointers during the decoding of RLE compressed data, which creates opportunities for attackers to manipulate the decoding process through carefully crafted malicious input.
The technical flaw manifests when the msrle_decode_8_16_24_32 function fails to properly validate or calculate boundary conditions during Microsoft RLE data processing. This function is responsible for decoding various bit depths of RLE compressed video data, including 8, 16, 24, and 32-bit formats. When processing malformed or crafted RLE data, the function does not correctly determine the end boundaries of data structures, leading to out-of-bounds memory access patterns. The vulnerability can be triggered when the decoder encounters RLE data that contains invalid or unexpected boundary markers, causing the decoder to read beyond allocated memory regions or write to unauthorized memory locations.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more severe consequences. Remote attackers can exploit this weakness to cause application crashes through out-of-bounds array access, effectively creating a denial of service scenario that can disrupt multimedia processing services. The vulnerability's potential for unspecified other impacts suggests that under certain conditions, attackers might be able to execute arbitrary code or gain additional privileges, making it particularly dangerous in environments where FFmpeg processes untrusted multimedia content. This type of vulnerability is particularly concerning for web applications, media servers, and content management systems that rely on FFmpeg for video processing.
The vulnerability aligns with CWE-129, which describes improper validation of array index bounds, and demonstrates characteristics consistent with ATT&CK technique T1203, involving exploitation of input validation weaknesses in multimedia processing components. Systems utilizing FFmpeg for video decoding operations are at risk when processing untrusted media files, particularly in scenarios where automated media processing occurs without proper input sanitization. The vulnerability's exploitation requires only the ability to deliver crafted RLE data to a system running the affected FFmpeg version, making it relatively easy to exploit in practice. Organizations should consider implementing input validation measures, updating to patched FFmpeg versions, and deploying network segmentation to limit exposure to this vulnerability.
Mitigation strategies should include immediate patching of FFmpeg installations to versions that address this vulnerability, typically those beyond 1.1.3. System administrators should also implement input validation measures for multimedia content, particularly when processing user-uploaded files or content from untrusted sources. Network-based protections can include filtering or blocking RLE-encoded content at network boundaries when such content is not required for legitimate operations. Additionally, implementing proper memory protection mechanisms such as stack canaries, address space layout randomization, and heap protection can help reduce the potential impact of exploitation attempts, though these measures are secondary to the primary requirement of applying the software patches.