CVE-2009-0100 in Excel
Summary
by MITRE
Microsoft Office Excel 2000 SP3, 2002 SP3, 2003 SP3, and 2007 SP1; Excel in Microsoft Office 2004 and 2008 for Mac; Microsoft Office Excel Viewer and Excel Viewer 2003 SP3; and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 do not properly parse the Excel spreadsheet file format, which allows remote attackers to execute arbitrary code via a crafted spreadsheet that contains a malformed object with "an offset and a two-byte value" that trigger a memory calculation error, aka "Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 09/01/2019
This vulnerability represents a critical memory corruption flaw in Microsoft Excel's file parsing mechanism that affects multiple versions across different platforms including Windows and Mac operating systems. The vulnerability stems from improper handling of Excel spreadsheet file formats where the application fails to correctly validate memory calculations when processing malformed objects containing specific offset and two-byte value parameters. This particular flaw demonstrates characteristics consistent with a classic buffer overflow condition where memory boundaries are exceeded during file parsing operations.
The technical implementation of this vulnerability involves the manipulation of Excel's internal file parser to trigger a memory calculation error through carefully crafted spreadsheet files. Attackers can exploit this by creating malicious Excel files that contain malformed objects with specific offset values and two-byte data structures designed to cause memory corruption during the parsing process. The vulnerability's exploitation requires precise control over the file format structure to manipulate the memory allocation calculations within Excel's processing engine.
From an operational perspective, this vulnerability presents a significant risk to enterprise environments where Excel files are frequently shared and opened across different systems. The remote execution capability means that simply opening a maliciously crafted spreadsheet file could result in arbitrary code execution on the target system without requiring user interaction beyond the standard file opening process. This makes the vulnerability particularly dangerous in phishing scenarios or when files are shared through untrusted channels within corporate networks.
The impact of this vulnerability extends beyond simple code execution to potentially enable full system compromise when combined with other attack vectors. Security researchers have classified this vulnerability as a memory corruption issue that could be leveraged for privilege escalation or persistent access to affected systems. Organizations using older versions of Microsoft Office that are no longer receiving security updates face the highest risk exposure from this vulnerability.
Mitigation strategies should focus on immediate patch deployment for all affected versions of Microsoft Office, including both Windows and Mac implementations. Network segmentation and email filtering should be implemented to prevent potentially malicious Excel files from reaching end users. Additionally, implementing application whitelisting policies and disabling automatic execution of Office files from untrusted sources can significantly reduce the attack surface. Organizations should also consider deploying endpoint protection solutions that can detect and block exploitation attempts targeting this specific vulnerability pattern.
This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a classic example of memory safety issues that have been addressed through improved input validation and memory management practices in modern software development. The ATT&CK framework would categorize this vulnerability under initial access and execution phases, specifically targeting the use of malicious files for code execution and potentially lateral movement within compromised environments. The vulnerability demonstrates the ongoing challenges in legacy software security where complex file format parsers continue to present attack surfaces that require continuous monitoring and remediation efforts.