CVE-2013-7013 in FFmpeg
Summary
by MITRE
The g2m_init_buffers function in libavcodec/g2meet.c in FFmpeg before 2.1 uses an incorrect ordering of arithmetic operations, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted Go2Webinar data.
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Analysis
by VulDB Data Team • 01/11/2022
The vulnerability identified as CVE-2013-7013 represents a critical flaw in the FFmpeg multimedia framework's handling of Go2Webinar data streams. This issue resides within the g2m_init_buffers function located in libavcodec/g2meet.c, where improper arithmetic operation sequencing creates exploitable conditions that can be leveraged by remote attackers. The flaw specifically manifests when processing malformed or crafted Go2Webinar content, which is a proprietary streaming format used by Go2Webinar software for web conferencing and training sessions. The vulnerability affects FFmpeg versions prior to 2.1, making it a significant concern for systems that rely on this multimedia processing library for handling various video and audio formats.
The technical root cause of this vulnerability stems from an incorrect ordering of arithmetic operations within the buffer initialization logic. When the g2m_init_buffers function processes incoming Go2Webinar data, it performs calculations to determine buffer sizes and memory allocations without proper validation of input parameters. This incorrect arithmetic sequencing leads to situations where calculated array indices or buffer boundaries exceed their intended limits, resulting in out-of-bounds memory access patterns. The flaw operates at the intersection of buffer management and input validation, where the absence of proper bounds checking allows attackers to manipulate the arithmetic operations to force memory corruption conditions. This type of vulnerability falls under the CWE-129 category of "Improper Validation of Array Index" and represents a classic example of how arithmetic overflow or underflow conditions can be exploited to compromise system stability and potentially enable further attack vectors.
The operational impact of CVE-2013-7013 extends beyond simple denial of service conditions to potentially encompass more severe consequences including arbitrary code execution or system compromise. Remote attackers can exploit this vulnerability by crafting specially formatted Go2Webinar data streams that trigger the flawed arithmetic operations during buffer initialization. The attack scenario typically involves an attacker sending maliciously constructed media content to a system running an affected FFmpeg version, which then processes this content through the vulnerable g2m_init_buffers function. Upon successful exploitation, the system may experience crashes, memory corruption, or in more sophisticated attack scenarios, potential code execution. This vulnerability is particularly concerning in environments where FFmpeg is used as a backend component for media processing services, streaming platforms, or content management systems that accept user-uploaded media files.
Mitigation strategies for CVE-2013-7013 primarily focus on immediate version updates and input validation enhancements. The most effective remediation involves upgrading to FFmpeg version 2.1 or later, where the arithmetic operation ordering has been corrected and proper bounds checking has been implemented. Organizations should also implement robust input validation measures that filter or reject suspicious Go2Webinar content before it reaches the vulnerable processing functions. Network-level defenses can include content inspection systems that identify and block potentially malicious media streams based on known patterns associated with this vulnerability. Additionally, system administrators should consider implementing application whitelisting policies that restrict execution of untrusted media processing operations and establish monitoring protocols to detect unusual memory access patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper arithmetic validation in multimedia processing libraries and aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution, particularly in scenarios where crafted inputs can trigger memory corruption conditions.