CVE-2021-40481 in Office
Summary
by MITRE • 10/13/2021
Microsoft Office Visio Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-40480.
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Analysis
by VulDB Data Team • 10/15/2021
Microsoft Office Visio contains a remote code execution vulnerability that arises from improper handling of specially crafted input files during the rendering process. This flaw exists in the way Visio processes certain file formats and can be exploited by attackers who deliver malicious documents to victims. The vulnerability stems from insufficient validation of user-supplied data within the application's file parsing logic, creating an opportunity for arbitrary code execution when legitimate users open compromised files.
The technical implementation of this vulnerability involves a buffer overflow condition that occurs when Visio attempts to parse malformed input within specific diagram elements. Attackers can craft Visio files containing malicious payloads that trigger memory corruption during rendering operations. This type of vulnerability is classified as a CWE-121 buffer overflow condition where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw specifically affects the application's handling of vector graphics and diagram objects that contain crafted malicious attributes or embedded content.
Operational impact of this vulnerability extends beyond simple remote code execution as it provides attackers with complete system compromise capabilities. Once exploited, the malicious code can execute with the privileges of the victim user, potentially allowing for lateral movement within networks, credential harvesting, or deployment of additional malware. The vulnerability is particularly dangerous in enterprise environments where Visio is commonly used for creating technical diagrams and business process models. Security researchers have noted that the exploitation requires minimal user interaction since opening a malicious file triggers the vulnerability automatically. This aligns with ATT&CK technique T1203, which describes exploitation of remote services through user interaction with malicious files.
Mitigation strategies for CVE-2021-40481 should include immediate deployment of Microsoft's security patches and updates to address the buffer overflow condition. Organizations should implement strict file validation policies that restrict the opening of Visio files from untrusted sources or implement sandboxing mechanisms for file processing. Network segmentation and email filtering solutions can help prevent delivery of malicious Visio files through phishing campaigns. Additionally, security awareness training for users should emphasize the importance of avoiding opening suspicious files, particularly those received via email or downloaded from untrusted websites. The vulnerability demonstrates the importance of secure coding practices and proper input validation as outlined in the OWASP Top Ten security principles. Organizations should also consider implementing application whitelisting policies that restrict execution of unauthorized Visio files and monitor for unusual file access patterns that may indicate exploitation attempts.