CVE-2010-3242 in Office
Summary
by MITRE
Microsoft Excel 2002 SP3, Office 2004 and 2008 for Mac, and Open XML File Format Converter for Mac do not properly validate record information, which allows remote attackers to execute arbitrary code via a crafted Excel document, aka "Ghost Record Type Parsing Vulnerability."
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Analysis
by VulDB Data Team • 09/26/2021
The vulnerability identified as CVE-2010-3242 represents a critical flaw in Microsoft Excel's handling of structured data records within spreadsheet files. This issue affects multiple versions including Excel 2002 SP3, Office 2004 and 2008 for Mac, and the Open XML File Format Converter for Mac, making it a widespread concern across Microsoft's legacy spreadsheet applications. The vulnerability stems from inadequate validation of record information during file parsing operations, creating a pathway for malicious actors to exploit the software through specially crafted malicious files.
The technical root cause of this vulnerability lies in the improper parsing of record types within Excel file formats, specifically in how the application handles what are known as "ghost records." When Excel encounters a malformed or unexpected record type in a spreadsheet file, the application fails to properly validate the record structure before processing it. This validation gap allows attackers to construct malicious Excel documents containing specially crafted record data that appears legitimate to the parser but contains executable code or data structures designed to trigger unexpected behavior in the application's memory management systems. The vulnerability operates under CWE-129, which describes improper validation of array indices, and can be categorized under ATT&CK technique T1203, which involves exploitation of software vulnerabilities through malicious file formats.
The operational impact of this vulnerability is severe as it enables remote code execution attacks without requiring user interaction beyond opening the malicious file. Attackers can construct Excel documents that, when opened by vulnerable applications, trigger buffer overflows or other memory corruption issues that can be exploited to execute arbitrary code with the privileges of the user running the application. This makes the vulnerability particularly dangerous in enterprise environments where users may inadvertently open malicious attachments or documents from untrusted sources. The attack vector is particularly insidious because it leverages the normal operation of spreadsheet applications, making detection and prevention more challenging.
Mitigation strategies for CVE-2010-3242 should include immediate deployment of Microsoft security updates and patches that address the record validation issues in affected versions. Organizations should implement strict file validation policies that prevent opening of untrusted Excel files, particularly those received via email or downloaded from unverified sources. Network-based protections such as email filtering and web proxies can help block malicious Excel documents before they reach end users. Additionally, security awareness training should emphasize the dangers of opening unexpected spreadsheet files and the importance of verifying document sources. For environments where the vulnerability cannot be immediately patched, administrators should consider disabling Excel file handling capabilities where possible and implementing application whitelisting policies that restrict execution of potentially vulnerable applications. The vulnerability demonstrates the critical importance of proper input validation in file format parsers and highlights the need for robust security testing of document processing components in office applications.