CVE-2000-0277 in Excel
Summary
by MITRE
Microsoft Excel 97 and 2000 does not warn the user when executing Excel Macro Language (XLM) macros in external text files, which could allow an attacker to execute a macro virus, aka the "XLM Text Macro" vulnerability.
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Analysis
by VulDB Data Team • 04/21/2026
The CVE-2000-0277 vulnerability represents a critical security flaw in Microsoft Excel 97 and 2000 versions that fundamentally compromised user safety through improper macro execution warnings. This vulnerability specifically targeted the Excel Macro Language execution environment when processing external text files, creating a dangerous pathway for malicious code deployment. The flaw exploited the lack of user notification mechanisms that should have alerted users to the potential risks of executing macros from external sources, thereby enabling attackers to silently deploy macro viruses without user awareness or consent.
The technical nature of this vulnerability stems from Excel's failure to implement proper security warnings when processing external text files containing XLM macro code. When users opened files that contained embedded macro commands, the application would execute these commands without alerting the user to their potentially malicious nature. This behavior created an environment where attackers could craft specially formatted text files that, when opened in Excel, would automatically execute harmful macro code. The vulnerability primarily affected versions that did not properly distinguish between trusted and untrusted macro execution contexts, particularly when these macros originated from external text files rather than native Excel files.
The operational impact of this vulnerability was severe and far-reaching, as it enabled widespread macro virus propagation across networks and individual systems. Attackers could distribute malicious text files through various means including email attachments, infected websites, or removable media, knowing that unsuspecting users would execute the embedded macros without warning. This created a significant risk for corporate environments where Excel was widely used for data processing and analysis, potentially allowing attackers to gain unauthorized access to systems, steal sensitive information, or disrupt business operations. The vulnerability essentially removed the user's ability to make informed decisions about macro execution, undermining fundamental security practices that should have protected against known threats.
This vulnerability aligns with CWE-347, which addresses improper verification of cryptographic signatures, and relates to broader ATT&CK techniques such as T1059.005 for Command and Scripting Interpreter and T1204.002 for User Execution through social engineering. Organizations affected by this vulnerability faced significant risk of macro virus infections that could persist across multiple systems and potentially provide attackers with persistent access to network resources. The lack of user warnings meant that even security-conscious users could unknowingly execute malicious code, making this vulnerability particularly dangerous in environments where users regularly opened external files for legitimate business purposes.
The recommended mitigations for CVE-2000-0277 involved immediate application of Microsoft security patches and updates to address the core macro execution flaw. Organizations should have implemented strict file handling policies that required verification of external files before opening them in Excel, including disabling automatic macro execution and requiring user confirmation for any macro operations. Additionally, security awareness training programs should have been enhanced to educate users about the risks of opening untrusted files and the importance of understanding macro execution warnings. Network administrators needed to implement monitoring systems to detect unusual macro activity patterns and ensure that all systems were running updated versions of Excel with proper security configurations. The vulnerability underscored the critical importance of maintaining current security patches and implementing layered security approaches to protect against social engineering attacks that exploit user trust in familiar applications.