CVE-2011-1279 in Excel
Summary
by MITRE
Microsoft Excel 2002 SP3 and 2003 SP3, Office 2004 and 2008 for Mac, and Open XML File Format Converter for Mac do not properly validate record information during parsing of Excel spreadsheets, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted spreadsheet, aka "Excel Out of Bounds WriteAV Vulnerability."
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Analysis
by VulDB Data Team • 11/09/2021
The CVE-2011-1279 vulnerability represents a critical memory corruption flaw in Microsoft Excel and related Office applications that affects multiple versions across different platforms. This vulnerability stems from inadequate validation of record information during the parsing process of Excel spreadsheet files, creating a pathway for malicious actors to exploit memory handling mechanisms within the software. The flaw specifically targets the way these applications process structured data within Excel files, particularly when encountering malformed or specially crafted records that exceed expected boundaries.
The technical implementation of this vulnerability involves an out-of-bounds write condition that occurs when Excel processes certain record structures within spreadsheet files. When the application encounters a crafted spreadsheet containing maliciously formatted records, it fails to properly validate the size or boundaries of these records before attempting to write data to memory locations. This validation failure results in memory corruption that can be leveraged by attackers to execute arbitrary code with the privileges of the user running the vulnerable application. The vulnerability is particularly dangerous because it can be triggered through legitimate file processing operations, making it difficult to detect and prevent through traditional user awareness measures.
From an operational perspective, this vulnerability presents significant risks to enterprise environments where Excel files are frequently shared and processed. The remote attack vector means that adversaries can deliver malicious payloads through email attachments, web downloads, or file sharing platforms without requiring physical access to target systems. The memory corruption aspect of the vulnerability can lead to both arbitrary code execution and denial of service conditions, providing attackers with multiple exploitation options. Organizations using older versions of Microsoft Office, particularly those that have not implemented proper patch management procedures, face heightened risk of compromise.
The vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and can be mapped to ATT&CK technique T1059.005 for execution through Microsoft Office applications. This mapping reflects how attackers can leverage Office applications as initial access points to establish persistent presence within target networks. The vulnerability also demonstrates characteristics of privilege escalation scenarios where successful exploitation can result in full system compromise. Organizations should consider implementing application whitelisting policies, email filtering solutions, and regular security updates to mitigate the risk associated with this vulnerability.
Mitigation strategies should focus on immediate patch deployment for all affected versions of Microsoft Office, including Excel 2002 SP3, 2003 SP3, Office 2004, and 2008 for Mac, along with the Open XML File Format Converter for Mac. Network administrators should implement strict file validation policies that scan incoming Excel files for suspicious patterns and malformed structures. Additionally, users should be trained to avoid opening Excel files from untrusted sources and to maintain current antivirus definitions. The vulnerability highlights the importance of maintaining comprehensive patch management programs and demonstrates how legacy software versions continue to pose significant security risks in modern enterprise environments where older applications remain in use.