CVE-1999-1259 in Office
Summary
by MITRE
Microsoft Office 98, Macintosh Edition, does not properly initialize the disk space used by Office 98 files and effectively inserts data from previously deleted files into the Office file, which could allow attackers to obtain sensitive information.
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Analysis
by VulDB Data Team • 04/20/2026
This vulnerability in Microsoft Office 98 Macintosh Edition represents a critical information disclosure flaw that stems from improper memory management during file creation and modification processes. The vulnerability occurs when Office 98 fails to properly zero out or securely erase disk space previously occupied by deleted files, allowing residual data from previous file operations to persist within new Office documents. This behavior creates a situation where sensitive information from previously deleted files can be inadvertently recovered through careful analysis of the newly created Office files. The flaw specifically affects the file allocation and storage mechanisms within the Macintosh operating system environment, where Office 98 does not implement proper secure deletion practices when creating new documents or modifying existing ones. This vulnerability is classified under CWE-225, which deals with improper handling of sensitive data during file operations, and represents a classic case of information leakage through inadequate data sanitization.
The technical exploitation of this vulnerability relies on the fundamental principle that modern file systems do not automatically overwrite deleted data with zeros or random patterns, leaving remnants of previous file contents in the allocated disk space. When Microsoft Office 98 creates new files or modifies existing ones, it allocates disk space without ensuring that this space is properly initialized to prevent data leakage. Attackers can exploit this by creating carefully crafted Office documents and then analyzing the underlying disk structure to recover sensitive information that was previously stored in the same disk sectors. This process typically involves examining the raw binary data of the Office file to identify patterns that correspond to previously deleted sensitive information, effectively bypassing normal access controls and security mechanisms. The vulnerability is particularly concerning because it operates at the file system level rather than the application level, making it difficult to detect and prevent through traditional application security measures.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially compromise entire security frameworks that rely on proper data sanitization practices. Organizations using Microsoft Office 98 on Macintosh systems face significant risks when handling sensitive documents, as the vulnerability allows unauthorized recovery of confidential information, personal data, or proprietary materials that may have been previously stored in the same disk locations. This creates a persistent threat where even deleted files can be reconstructed, undermining the security assumptions of data deletion and privacy protection. The vulnerability affects not only individual users but also enterprise environments where Office 98 may be used for document creation, collaboration, and information sharing. The implications are particularly severe in regulated environments where data protection requirements mandate secure deletion of sensitive information, as this vulnerability directly contradicts those security requirements. According to ATT&CK framework, this vulnerability maps to T1070.004 (File Deletion) and T1566 (Phishing), as it can be exploited through social engineering tactics where attackers might create seemingly legitimate Office files that contain hidden sensitive information.
Mitigation strategies for this vulnerability require a multi-layered approach that addresses both the immediate technical issue and broader security practices. System administrators should implement regular disk sanitization procedures and ensure that Office 98 installations are properly configured to handle file creation with appropriate security measures. The most effective immediate solution involves upgrading to newer versions of Microsoft Office that properly implement secure file creation and deletion practices, as Microsoft addressed this specific vulnerability in subsequent releases. Organizations should also consider implementing additional security controls such as disk encryption, regular security audits, and data loss prevention measures to protect against potential exploitation of this vulnerability. Network security measures including intrusion detection systems and endpoint protection can help monitor for suspicious file creation patterns that might indicate exploitation attempts. The vulnerability highlights the importance of secure coding practices and proper memory management in application development, particularly when dealing with file system operations and data persistence mechanisms. Organizations should also establish clear policies regarding document handling, data sanitization, and secure deletion procedures to minimize the risk of information leakage through similar vulnerabilities in other applications.