CVE-2012-0855 in FFmpeg
Summary
by MITRE
Heap-based buffer overflow in the get_sot function in the J2K decoder (j2k.c) in libavcodec in FFmpeg before 0.9.1 allows remote attackers to cause a denial of service (application crash) via unspecified vectors related to the curtileno variable.
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Analysis
by VulDB Data Team • 12/12/2021
The vulnerability identified as CVE-2012-0855 represents a critical heap-based buffer overflow within the FFmpeg multimedia framework's JPEG 2000 decoder component. This flaw exists in the get_sot function located in the j2k.c file within libavcodec, which is a core library responsible for decoding various audio and video formats. The vulnerability specifically manifests when processing maliciously crafted JPEG 2000 files, where the curtileno variable becomes manipulated in a manner that leads to memory corruption. The flaw affects FFmpeg versions prior to 0.9.1, making it a significant concern for systems utilizing older versions of this widely deployed multimedia processing library.
The technical implementation of this vulnerability stems from improper bounds checking within the get_sot function, which processes the SOT (Start of Tile) marker in JPEG 2000 files. When the curtileno variable is processed, the decoder fails to validate the input data against expected buffer boundaries, allowing an attacker to provide malformed data that exceeds allocated heap memory space. This heap overflow condition occurs during the parsing of JPEG 2000 tile information, where the decoder attempts to write data beyond the allocated buffer region, resulting in memory corruption that can trigger application instability. The vulnerability is classified as a heap-based buffer overflow under CWE-122, which specifically addresses insufficient checking of the relationship between the number of bytes copied and the size of the destination buffer, making it a direct descendant of the broader CWE-119 category for memory safety issues.
The operational impact of this vulnerability extends beyond simple denial of service, as it can be exploited by remote attackers to cause application crashes that may be leveraged as part of larger attack chains. Systems utilizing FFmpeg for processing user-uploaded content, media transcoding services, or streaming applications become particularly vulnerable since they may encounter malformed JPEG 2000 files from untrusted sources. The remote exploitation capability means that attackers can trigger the vulnerability without requiring local access, making it a significant threat to web applications, content management systems, and media processing servers. From an ATT&CK framework perspective, this vulnerability maps to the T1203 technique for Exploitation for Client Execution, as it can be used to compromise systems through malicious media file delivery.
Mitigation strategies for CVE-2012-0855 primarily focus on immediate version upgrades to FFmpeg 0.9.1 or later, which contain the necessary patches to address the buffer overflow condition. Organizations should also implement input validation measures that sanitize JPEG 2000 file content before processing, particularly when handling untrusted media uploads. Additionally, deploying network-based intrusion prevention systems that can detect and block suspicious JPEG 2000 file patterns may provide additional defense-in-depth. System administrators should conduct comprehensive vulnerability assessments to identify all systems running affected FFmpeg versions and prioritize patching based on risk exposure. The remediation approach aligns with NIST's vulnerability management guidelines, emphasizing the importance of timely patch deployment and proper system hardening measures to prevent exploitation of known memory corruption vulnerabilities.