CVE-2021-1713 in Excel
Summary
by MITRE • 01/13/2021
Microsoft Excel Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-1714.
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Analysis
by VulDB Data Team • 05/04/2025
Microsoft Excel contains a remote code execution vulnerability that arises from improper handling of specially crafted files during the parsing process. This flaw exists in the way Excel processes certain data structures within workbook files, specifically when handling malformed or maliciously constructed spreadsheet elements. The vulnerability stems from a lack of proper input validation and bounds checking within the application's file parsing engine, allowing an attacker to craft malicious Excel files that can trigger unintended code execution when opened by vulnerable systems.
The technical exploitation of this vulnerability occurs through a buffer overflow condition that manifests when Excel attempts to parse corrupted or specially constructed data within cell formulas or embedded objects. Attackers can leverage this flaw by preparing malicious .xls or .xlsx files containing crafted payloads that, when opened by an affected version of Microsoft Excel, cause the application to execute arbitrary code with the privileges of the current user. The vulnerability is particularly dangerous because it can be triggered through simple file opening actions, making it an ideal candidate for phishing attacks and social engineering campaigns.
The operational impact of CVE-2021-1713 extends beyond individual system compromise to potentially enable broader network infiltration and lateral movement within enterprise environments. Once an attacker achieves code execution through this vulnerability, they can establish persistence mechanisms, escalate privileges, and access sensitive data stored within the compromised system. The vulnerability affects multiple versions of Microsoft Excel across different operating systems, including Windows and macOS platforms, making it a significant threat vector for organizations that rely heavily on spreadsheet applications for business operations.
Organizations should implement immediate mitigations including applying Microsoft's security patches released in the February 2021 security updates, configuring application control policies to restrict Excel execution in high-risk environments, and implementing email filtering mechanisms to prevent the delivery of potentially malicious Excel files. Network segmentation and monitoring solutions should be deployed to detect anomalous Excel file access patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-121 and CWE-125 categories related to buffer overflow conditions and improper input validation, and maps to ATT&CK techniques including T1059 for command and script interpreter and T1078 for valid accounts to maintain persistence within compromised systems.
Security teams should also consider implementing automated threat hunting procedures that focus on identifying suspicious Excel file operations, particularly those involving macro-enabled files or files with unusual formatting patterns. Regular security awareness training for end users should emphasize the dangers of opening unexpected Excel attachments and the importance of verifying file sources before execution. The vulnerability demonstrates the critical importance of maintaining up-to-date software patches and implementing defense-in-depth strategies that protect against multiple attack vectors simultaneously, as Excel remains a common target for initial compromise in enterprise security incidents.