CVE-2000-0788 in Word
Summary
by MITRE
The Mail Merge tool in Microsoft Word does not prompt the user before executing Visual Basic (VBA) scripts in an Access database, which could allow an attacker to execute arbitrary commands.
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Analysis
by VulDB Data Team • 06/25/2021
The vulnerability described in CVE-2000-0788 represents a critical security flaw in Microsoft Word's Mail Merge functionality that operates under the weakness category identified by CWE-94, which encompasses the execution of unintended code or commands. This vulnerability specifically affects the interaction between Microsoft Word and Access databases, creating a scenario where user consent is not required for the execution of Visual Basic for Applications scripts. The flaw exists within the design of the Mail Merge tool that allows Word to automatically process and execute VBA macros contained within Access database files without any user intervention or explicit confirmation. This behavior creates a significant attack surface where malicious actors can exploit the trust relationship between Word and Access database files to execute arbitrary code on vulnerable systems.
The technical implementation of this vulnerability stems from the lack of proper input validation and user consent mechanisms within the Mail Merge process. When a user opens a document containing a Mail Merge field that references an Access database, the system automatically attempts to execute any VBA scripts present in the database without prompting the user for permission. This automated execution bypasses normal security controls that would typically require user confirmation before running potentially malicious code. The vulnerability is particularly dangerous because it leverages the legitimate functionality of Microsoft Office applications to deliver malicious payloads, making it difficult to distinguish between benign and malicious operations. The flaw operates at the application layer and can be triggered through various attack vectors including email attachments, malicious documents, or web-based delivery mechanisms.
The operational impact of CVE-2000-0788 extends beyond simple code execution to encompass a wide range of potential security breaches that align with tactics described in the MITRE ATT&CK framework under the execution and privilege escalation domains. Attackers can utilize this vulnerability to install backdoors, steal sensitive data, or establish persistent access to compromised systems. The vulnerability affects users across different versions of Microsoft Office, making it a widespread concern that impacts organizations of all sizes. The attack requires minimal user interaction beyond opening a malicious document, which means that even security-conscious users can be compromised through social engineering attacks that deliver documents containing malicious Mail Merge references. This vulnerability also demonstrates the importance of the principle of least privilege and proper application sandboxing, as the execution of VBA macros should not automatically occur without explicit user consent.
Mitigation strategies for this vulnerability should focus on multiple layers of defense as recommended by cybersecurity best practices and aligned with the MITRE ATT&CK framework's prevention recommendations. Organizations should disable the automatic execution of VBA macros in Office applications through registry modifications or group policy settings, implement strict email filtering and content scanning, and educate users about the risks of opening documents from untrusted sources. The vulnerability highlights the necessity of maintaining up-to-date security patches and following the principle of defense in depth. System administrators should consider implementing macro security policies that require explicit user approval before executing any VBA code, particularly when dealing with external database connections. Additionally, network segmentation and monitoring solutions should be deployed to detect anomalous behavior patterns that may indicate exploitation attempts, as the automatic execution of scripts without user awareness makes detection more challenging. This vulnerability serves as a historical example of why proper input validation and user consent mechanisms are essential components of secure software design, particularly in applications that handle external data sources and automated processing functions.