CVE-2007-1756 in Excel
Summary
by MITRE
Microsoft Excel 2000 SP3, 2002 SP3, 2003 SP2, 2003 Viewer, and Office Excel 2007 does not properly validate version information, which allows user-assisted remote attackers to execute arbitrary code via a crafted Excel file, aka "Calculation Error Vulnerability".
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 07/21/2019
The CVE-2007-1756 vulnerability represents a critical calculation error in Microsoft Excel software across multiple versions including Excel 2000 SP3, 2002 SP3, 2003 SP2, 2003 Viewer, and Office Excel 2007. This vulnerability falls under the CWE-129 weakness category, specifically addressing improper validation of input data during calculation processes. The flaw manifests when Excel fails to properly validate version information within spreadsheet files, creating a condition where maliciously crafted Excel files can trigger arbitrary code execution. This vulnerability operates as a user-assisted remote attack vector, meaning that a user must interact with the malicious file for the exploit to succeed, typically through opening or processing the crafted spreadsheet.
The technical implementation of this vulnerability stems from Excel's calculation engine failing to properly validate version information contained within Excel file headers or metadata. When Excel processes a maliciously crafted file, the improper version validation allows attackers to manipulate the calculation engine's behavior through carefully constructed cell references or formula structures. This manipulation can lead to buffer overflows or other memory corruption conditions that enable attackers to execute arbitrary code with the privileges of the user running Excel. The vulnerability specifically impacts the calculation engine's handling of version-specific data structures, allowing attackers to bypass normal execution boundaries and inject malicious instructions into the application's memory space.
The operational impact of CVE-2007-1756 extends beyond simple code execution to encompass significant security risks for enterprise environments. Organizations using affected Excel versions face potential compromise through social engineering attacks where users unknowingly open malicious spreadsheets delivered via email attachments or malicious websites. The vulnerability's remote exploitation capability means that attackers can leverage this flaw without requiring physical access to target systems, making it particularly dangerous for organizations with limited security controls. This vulnerability maps to the ATT&CK technique T1059.005 for command and scripting interpreter, as attackers can execute arbitrary code through the vulnerable calculation engine. The attack surface is particularly broad given Excel's widespread use across business environments and the common practice of opening spreadsheet files from external sources without proper security validation.
Mitigation strategies for CVE-2007-1756 require both immediate patch management and operational security improvements. Microsoft released security updates for all affected versions, and organizations should prioritize deployment of these patches to eliminate the vulnerability. Additionally, implementing strict file validation policies that restrict Excel file processing from untrusted sources can significantly reduce risk exposure. Network security controls such as email filtering and web content filtering should be enhanced to block suspicious Excel files before they reach end users. Security awareness training programs should educate users about the dangers of opening unexpected spreadsheet files and the importance of verifying file sources. Organizations should also consider implementing application whitelisting policies that restrict Excel execution to trusted environments and regularly audit their Excel usage patterns to identify potential exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation in spreadsheet applications and highlights the need for robust security practices in widely deployed software applications.