CVE-2024-20677 is a high-severity heap-based buffer overflow vulnerability (CWE-122) found in Microsoft 3D Viewer version 7.0.0. The vulnerability arises from the handling of FBX files, a common 3D model format. Specifically, the flaw allows an attacker to craft a malicious FBX file that, when processed by 3D Viewer or when inserted into Microsoft Office applications (Word, Excel, PowerPoint, Outlook) that support FBX insertion, could lead to remote code execution (RCE). The vulnerability impacts the confidentiality, integrity, and availability of affected systems by enabling arbitrary code execution with the privileges of the user running the application. Exploitation requires user interaction (opening or inserting a malicious FBX file) but does not require prior authentication. The attack vector is local (AV:L), meaning the attacker must have the ability to deliver the malicious file to the victim, for example via email or file sharing. Microsoft has mitigated this vulnerability by disabling the ability to insert FBX files in Office applications and 3D Viewer as of January 9, 2024, and February 13, 2024, respectively. Existing 3D models inserted from FBX files continue to function unless they used the 'Link to File' option, which now is disabled. No known exploits are currently reported in the wild. The CVSS v3.1 score is 7.8 (high), reflecting the significant impact and relatively low complexity of exploitation, though requiring user interaction. This vulnerability highlights risks associated with processing complex 3D model files within widely used productivity software and specialized viewers, emphasizing the need for secure parsing and input validation in multimedia components.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Microsoft Office products and 3D Viewer in various sectors including engineering, design, education, and corporate environments. Successful exploitation could lead to remote code execution, allowing attackers to execute arbitrary code, potentially leading to data breaches, espionage, ransomware deployment, or disruption of business operations. Confidentiality could be compromised by unauthorized access to sensitive documents; integrity could be undermined by tampering with files or system configurations; availability could be affected by system crashes or denial-of-service conditions. The requirement for user interaction (opening or inserting a malicious FBX file) means phishing or social engineering campaigns could be leveraged to deliver the exploit. European organizations with workflows involving 3D models or collaborative document editing are particularly at risk. The disabling of FBX insertion functionality may impact business processes relying on this feature, requiring adjustments or alternative workflows. However, this mitigation reduces the attack surface and protects organizations from exploitation until a full patch or fix is available.

Beyond the immediate disabling of FBX file insertion in Office and 3D Viewer, European organizations should implement the following specific mitigations: 1) Educate users about the risks of opening unsolicited or unexpected FBX files, especially from unknown or untrusted sources, to reduce the risk of social engineering attacks. 2) Employ advanced email filtering and attachment sandboxing to detect and block malicious FBX files before they reach end users. 3) Monitor and restrict the use of 3D Viewer and Office applications to trusted users and environments, applying application control policies to limit execution of unapproved software. 4) Regularly audit documents and workflows to identify any reliance on FBX insertion features and develop alternative secure workflows if necessary. 5) Maintain up-to-date endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts. 6) Apply the latest Microsoft security updates promptly and monitor Microsoft advisories for any patches or further mitigations related to this vulnerability. 7) Consider network segmentation to isolate systems that handle 3D models or sensitive Office documents to limit lateral movement in case of compromise.