CVE-2008-4264 in Excel
Summary
by MITRE
Microsoft Office Excel 2000 SP3, 2002 SP3, 2003 SP3, and 2007 Gold and SP1; Excel Viewer 2003 Gold and SP3; Excel Viewer; Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Gold and SP1; Office 2004 and 2008 for Mac; and Open XML File Format Converter for Mac allow remote attackers to execute arbitrary code via a crafted Excel spreadsheet that contains a malformed formula, which triggers "pointer corruption" during the loading of formulas from this spreadsheet, aka "File Format Parsing Vulnerability."
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Analysis
by VulDB Data Team • 08/21/2019
This vulnerability represents a critical file format parsing flaw in Microsoft Office Excel products spanning multiple versions and platforms. The vulnerability stems from inadequate input validation during the processing of malformed formulas within Excel spreadsheet files, creating a scenario where attacker-controlled data can trigger memory corruption issues. The specific technical mechanism involves pointer corruption during formula loading operations, which occurs when Excel attempts to parse crafted spreadsheet elements that do not conform to expected data structures. This type of vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, though the manifestation through pointer corruption suggests more complex memory management issues. The vulnerability affects a broad range of Microsoft Office products including Excel 2000 through 2007, various viewer versions, and Mac-specific implementations, indicating a widespread impact across different product lines and operating systems.
The operational impact of this vulnerability is severe as it enables remote code execution without requiring user interaction beyond opening the malicious file. Attackers can craft specially designed Excel spreadsheets containing malformed formulas that, when processed by vulnerable Excel versions, cause the application to corrupt memory pointers and subsequently execute arbitrary code with the privileges of the user running Excel. This represents a classic exploit chain where file format parsing errors lead to privilege escalation opportunities. The vulnerability's remote attack vector means that malicious actors can deliver payloads through email attachments, web downloads, or file sharing systems without needing physical access to target systems. The exploitation process typically involves creating a spreadsheet with carefully constructed formula elements that trigger the pointer corruption during normal spreadsheet loading operations, which aligns with the ATT&CK technique T1068 for Local Privilege Escalation and T1203 for Exploitation for Client Execution.
Mitigation strategies for this vulnerability require immediate patching of affected Microsoft Office versions, as Microsoft released security updates specifically addressing this issue. Organizations should implement strict file validation policies, particularly for Excel files received from untrusted sources, and consider deploying application whitelisting solutions to prevent execution of unauthorized Office applications. Network-based protections such as email filtering and web proxy scanning can help identify and block malicious Excel files before they reach end users. Additionally, users should be educated about the dangers of opening unexpected Excel files and the importance of keeping Office applications updated with the latest security patches. The vulnerability demonstrates the critical importance of proper input validation and memory management in office productivity software, as these applications must process untrusted data from various sources while maintaining system integrity. Organizations should also consider implementing sandboxing technologies for Excel processing and monitoring for unusual memory access patterns that might indicate exploitation attempts, particularly given the widespread nature of affected products and the remote execution capability.