CVE-2021-45948 in Open Asset Import Library
Summary
by MITRE • 01/01/2022
Open Asset Import Library (aka assimp) 5.1.0 and 5.1.1 has a heap-based buffer overflow in _m3d_safestr (called from m3d_load and Assimp::M3DWrapper::M3DWrapper).
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Analysis
by VulDB Data Team • 01/05/2022
The Open Asset Import Library commonly known as assimp represents a critical component in the 3d graphics ecosystem, serving as a universal asset importer that enables applications to load various 3d file formats. This library is widely adopted across gaming engines, design tools, and visualization platforms, making its security paramount to the broader digital infrastructure. The vulnerability under discussion affects versions 5.1.0 and 5.1.1 of this library, specifically targeting the m3d file format loader within the asset import framework. The issue manifests as a heap-based buffer overflow that occurs during the processing of m3d files, which are commonly used in 3d modeling and animation applications. This vulnerability impacts the core functionality of the library and can potentially affect any application that utilizes assimp for m3d file processing, creating a significant attack surface for malicious actors seeking to exploit this weakness.
The technical flaw resides in the _m3d_safestr function which is invoked from both m3d_load and Assimp::M3DWrapper::M3DWrapper methods within the library's codebase. This function appears to improperly handle string operations when processing m3d file data, leading to a situation where memory allocation does not adequately account for the actual data size being processed. The buffer overflow occurs when the library attempts to copy or process string data from m3d files without sufficient bounds checking, allowing an attacker to potentially write beyond allocated memory boundaries. This type of vulnerability falls under the common weakness enumeration CWE-121, which categorizes heap-based buffer overflows as a critical class of memory safety issues. The flaw demonstrates a classic insufficient boundary check problem where the library fails to validate input data length against allocated buffer space, creating opportunities for memory corruption that can be exploited by adversaries.
The operational impact of this vulnerability extends beyond simple application crashes, as it creates potential for remote code execution when exploited. An attacker who can craft a malicious m3d file could potentially leverage this buffer overflow to execute arbitrary code on systems running vulnerable applications. This threat is particularly concerning given that assimp is integrated into numerous commercial and open-source applications, including popular game engines like Unreal Engine and Unity, 3d modeling software, and various visualization platforms. The vulnerability affects the entire ecosystem of applications that depend on assimp for 3d asset handling, meaning that exploitation could compromise multiple software products simultaneously. The attack vector typically involves the delivery of a malicious m3d file through various means such as email attachments, compromised websites, or file sharing platforms, where unsuspecting users might open or process these files through vulnerable applications.
Mitigation strategies for this vulnerability primarily involve immediate remediation through version updates to assimp 5.1.2 or later, which contains the necessary patches to address the buffer overflow issue. Organizations should prioritize patching all systems running vulnerable versions of the library, particularly those handling untrusted 3d asset files from external sources. Security teams should implement additional safeguards such as input validation, sandboxing of 3d file processing, and network monitoring for suspicious file transfers. The vulnerability also highlights the importance of proper code review practices and automated security testing for libraries handling binary file formats, as demonstrated by the ATT&CK framework's emphasis on software supply chain attacks. System administrators should consider implementing application whitelisting policies to restrict execution of known vulnerable applications until proper updates are deployed, while also monitoring for potential exploitation attempts through network traffic analysis and endpoint detection systems that can identify anomalous file processing behaviors.