CVE-2007-0031 in Office
Summary
by MITRE
Heap-based buffer overflow in Microsoft Excel 2000 SP3, 2002 SP3, 2003 SP2, 2004 for Mac, and v.X for Mac allows user-assisted remote attackers to execute arbitrary code via a BIFF8 spreadsheet with a PALETTE record that contains a large number of entries.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability identified as CVE-2007-0031 represents a critical heap-based buffer overflow affecting multiple versions of Microsoft Excel across different platforms including Windows and Mac operating systems. This flaw resides within the parsing mechanism of BIFF8 spreadsheet format files, specifically when processing PALETTE records that contain an excessive number of color entries. The vulnerability stems from insufficient input validation and bounds checking during the interpretation of spreadsheet metadata, creating a condition where maliciously crafted color palette data can overwrite adjacent memory locations in the application's heap memory space.
The technical implementation of this vulnerability exploits the inherent structure of Microsoft Excel's spreadsheet parsing engine by leveraging the BIFF8 file format specification which defines how spreadsheet data should be stored and interpreted. When Excel encounters a PALETTE record containing an unusually large number of color entries, the application fails to properly validate the record size against allocated memory boundaries. This allows an attacker to craft a malicious spreadsheet file that, when opened by an affected Excel version, triggers memory corruption through heap overflow conditions. The flaw operates at the application layer where spreadsheet parsing occurs, making it particularly dangerous as it requires no privileged access and can be executed through user interaction with a malicious file.
From an operational perspective, this vulnerability creates significant risk for organizations as it enables remote code execution through user-assisted attacks where victims must open a specially crafted malicious spreadsheet file. The attack vector is particularly concerning because it can be delivered through email attachments, web downloads, or shared network locations without requiring any special privileges or system-level access. The exploit chain typically involves an attacker creating a malicious BIFF8 file with oversized PALETTE records that, when processed by the vulnerable Excel application, cause stack corruption leading to arbitrary code execution. This vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution and CWE-121 - Stack-based Buffer Overflow, demonstrating how improper buffer handling in legacy spreadsheet applications can be weaponized for remote compromise.
The impact of this vulnerability extends beyond individual user systems to potentially affect entire enterprise environments where Microsoft Excel remains a widely deployed application for data processing and analysis. Organizations running affected Excel versions are particularly vulnerable as the flaw exists in core spreadsheet processing functionality that is frequently used across business operations. The exploitation requires minimal sophistication from attackers and can be automated through social engineering campaigns targeting end users. Mitigation strategies should include immediate patching of affected Excel versions, implementation of strict file validation policies for spreadsheet files, and user education about avoiding untrusted spreadsheet attachments. Network-level controls such as email filtering and web proxy restrictions can provide additional protection layers, while application whitelisting and sandboxing approaches can further reduce the attack surface. Organizations should also consider implementing macro security policies and disabling automatic execution of macros in spreadsheet files to minimize the risk of exploitation.