CVE-2000-0597 in Internet Explorer
Summary
by MITRE
Microsoft Office 2000 (Excel and PowerPoint) and PowerPoint 97 are marked as safe for scripting, which allows remote attackers to force Internet Explorer or some email clients to save files to arbitrary locations via the Visual Basic for Applications (VBA) SaveAs function, aka the "Office HTML Script" vulnerability.
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Analysis
by VulDB Data Team • 04/07/2017
The CVE-2000-0597 vulnerability represents a critical security flaw in Microsoft Office applications that exploited the trust relationship between Office and Internet Explorer through Visual Basic for Applications scripting capabilities. This vulnerability specifically affected Microsoft Office 2000 including Excel and PowerPoint, as well as PowerPoint 97, where these applications were configured with scripting permissions that could be leveraged by malicious actors to execute unauthorized file operations. The flaw stemmed from the improper handling of the VBA SaveAs function within the Office environment, which allowed attackers to manipulate the file saving process through HTML-based attacks.
The technical exploitation of this vulnerability occurred through the manipulation of HTML content that would trigger the Office applications to save files to arbitrary locations on the victim's system. When users opened maliciously crafted HTML documents or received infected email attachments, the Office applications would execute VBA code that utilized the SaveAs function to write files to predetermined locations without proper user consent or awareness. This behavior was particularly dangerous because Office applications were marked as safe for scripting, meaning they could execute VBA macros without prompting users for confirmation, effectively bypassing standard security warnings that would normally alert users to potentially harmful operations.
The operational impact of this vulnerability was significant as it enabled attackers to perform persistent malicious activities through file system manipulation. Attackers could leverage this vulnerability to install backdoors, malware, or other malicious components in strategic locations on the victim's system, potentially gaining persistent access to the compromised machine. The ability to save files to arbitrary locations allowed attackers to bypass traditional security measures that might monitor network traffic or specific file types, as the malicious files were written directly to the local file system. This vulnerability particularly affected organizations where users had elevated privileges or where Office applications were frequently used to open email attachments or web content.
This vulnerability aligns with CWE-74, which describes "Improper Neutralization of Special Elements in Output Used by a Downstream Component" and relates to CWE-94, "Improper Control of Generation of Code ('Code Injection')." The attack pattern follows ATT&CK techniques including T1059.005 for Visual Basic and T1133 for External Remote Services, as attackers could leverage the Office applications to execute code remotely through web-based attacks. The vulnerability also demonstrates characteristics of T1078.004 for Valid Accounts, as the exploitation required legitimate user accounts with Office applications installed and configured to allow scripting. Organizations were particularly vulnerable when users opened email attachments or navigated to malicious websites that contained HTML content designed to exploit this specific flaw in Office's VBA handling capabilities.
Mitigation strategies for CVE-2000-0597 focused on several key approaches including disabling VBA macro execution, implementing proper email filtering and content validation, and restricting Office applications from being marked as safe for scripting. Microsoft released patches to address the vulnerability by modifying the default security settings for Office applications and implementing additional validation checks for the SaveAs function. Organizations should have implemented security policies that required user confirmation before executing macros, deployed email security solutions that could detect and block malicious HTML content, and ensured that Office applications were not configured with overly permissive security settings. The vulnerability highlighted the importance of maintaining proper security boundaries between applications and the need for comprehensive security awareness training to prevent users from inadvertently triggering malicious code execution through seemingly benign Office documents.