CVE-2020-1504 in Excel
Summary
by MITRE
A remote code execution vulnerability exists in Microsoft Excel software when the software fails to properly handle objects in memory. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the current user. If the current user is logged on with administrative user rights, an attacker could take control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. Exploitation of the vulnerability requires that a user open a specially crafted file with an affected version of Microsoft Excel. In an email attack scenario, an attacker could exploit the vulnerability by sending the specially crafted file to the user and convincing the user to open the file. In a web-based attack scenario, an attacker could host a website (or leverage a compromised website that accepts or hosts user-provided content) containing a specially crafted file designed to exploit the vulnerability. An attacker would have no way to force users to visit the website. Instead, an attacker would have to convince users to click a link, typically by way of an enticement in an email or instant message, and then convince them to open the specially crafted file. The security update addresses the vulnerability by correcting how Microsoft Excel handles objects in memory.
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Analysis
by VulDB Data Team • 02/23/2026
The vulnerability identified as CVE-2020-1504 represents a critical remote code execution flaw in Microsoft Excel software that stems from improper handling of objects in memory. This vulnerability falls under the CWE-125 Out-of-bounds Read category, where Excel fails to properly validate memory objects during processing, creating a pathway for malicious code execution. The flaw exists in the way Excel parses and manages memory structures when processing specially crafted files, allowing attackers to manipulate memory contents and execute arbitrary code with the privileges of the currently logged-on user. This vulnerability directly maps to ATT&CK technique T1059.001 Command and Scripting Interpreter, as exploitation involves executing code within the target system's context.
The exploitation of CVE-2020-1504 requires user interaction through opening a malicious file, making it a classic social engineering target that aligns with ATT&CK technique T1566.001 Phishing. Attackers can deliver malicious Excel files through various vectors including email attachments, web-based attacks on compromised websites, or by leveraging user trust in legitimate content. The vulnerability's impact is particularly severe when users operate with administrative privileges, as successful exploitation could lead to complete system compromise. The attack chain typically begins with an attacker crafting a malicious Excel file that contains specially designed memory structures, followed by social engineering to convince the user to open the file, which then triggers the memory corruption and code execution. This attack model demonstrates the importance of both technical controls and user awareness training in cybersecurity defense.
The technical mechanism behind this vulnerability involves memory management failures during Excel's object processing routines, where insufficient validation of memory objects allows attackers to manipulate heap memory structures. When Excel attempts to process the malicious file, the improper memory handling creates opportunities for buffer overflows or memory corruption that can be leveraged to execute attacker-controlled code. The security update provided by Microsoft addresses this issue by implementing proper memory validation and object handling procedures, ensuring that Excel correctly manages memory objects during file processing. This fix aligns with security best practices outlined in the OWASP Top Ten and Microsoft's own security development lifecycle. The remediation approach focuses on strengthening input validation and memory management controls, which are fundamental defenses against memory corruption vulnerabilities. Organizations should prioritize immediate deployment of the security update as the primary mitigation strategy, while also implementing email filtering controls and user education programs to reduce the risk of successful exploitation through social engineering vectors.