CVE-2011-1276 in Excel
Summary
by MITRE
Buffer overflow in Microsoft Excel 2002 SP3, 2003 SP3, and 2007 SP2; Office 2004 and 2008 for Mac; Open XML File Format Converter for Mac; Excel Viewer SP2; and Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP2 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted Excel spreadsheet, related to improper validation of record information, aka "Excel Buffer Overrun Vulnerability."
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Analysis
by VulDB Data Team • 02/22/2025
The CVE-2011-1276 vulnerability represents a critical buffer overflow flaw affecting multiple Microsoft Office products including Excel 2002 SP3, 2003 SP3, and 2007 SP2, along with Office 2004 and 2008 for Mac, Open XML File Format Converter for Mac, Excel Viewer SP2, and the Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP2. This vulnerability stems from inadequate validation of record information within Excel spreadsheet files, creating a condition where maliciously crafted spreadsheet data can trigger memory corruption. The flaw operates at the core of Excel's file parsing mechanism, specifically targeting how the application processes structured data within spreadsheet files. The vulnerability manifests when Excel attempts to read and process malformed record structures, leading to improper memory allocation and subsequent buffer overrun conditions. This type of vulnerability falls under CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The attack vector requires remote code execution through specially crafted Excel files, making it particularly dangerous in environments where users frequently open spreadsheet documents from untrusted sources.
The operational impact of this vulnerability extends beyond simple memory corruption to encompass full system compromise capabilities. When exploited, the buffer overflow can lead to arbitrary code execution with the privileges of the user running Excel, potentially enabling attackers to install malware, modify system files, or establish persistent backdoors. The denial of service aspect of this vulnerability can also be leveraged to disrupt business operations by causing Excel applications to crash repeatedly, thereby preventing legitimate users from accessing critical spreadsheet data. Attackers typically craft malicious Excel files containing oversized or malformed record structures that exceed the allocated buffer space, causing the application to write data beyond its intended memory boundaries. This memory corruption can overwrite critical program execution pointers, return addresses, or other essential data structures, allowing attackers to redirect program flow and execute malicious code. The vulnerability affects both Windows and Mac platforms, demonstrating the widespread nature of the flaw across Microsoft's product ecosystem. According to ATT&CK framework, this vulnerability maps to T1059.005 (Command and Scripting Interpreter: Visual Basic), as attackers can leverage the buffer overflow to execute malicious Visual Basic macros or other code within the Excel environment.
Mitigation strategies for CVE-2011-1276 require immediate patch application from Microsoft, as the company released security updates specifically addressing this vulnerability. Organizations should implement comprehensive patch management processes to ensure all affected Office installations receive the necessary security updates. Additionally, security administrators should deploy application whitelisting solutions to restrict execution of unsigned or untrusted Excel files, while implementing email filtering measures to prevent malicious spreadsheet attachments from reaching end users. Network segmentation and privilege separation can help limit the potential impact if an attacker successfully exploits this vulnerability, ensuring that compromised Excel processes cannot access critical system resources. Regular security awareness training for users can also reduce the likelihood of successful exploitation by teaching employees to recognize suspicious spreadsheet attachments and avoid opening files from untrusted sources. The vulnerability highlights the importance of proper input validation and bounds checking in software development, particularly for applications that process structured data formats like spreadsheet files. Organizations should also consider implementing sandboxing solutions for Excel processing, creating isolated execution environments that can contain potential exploits and prevent them from affecting the broader system infrastructure. Microsoft's security advisory for this vulnerability emphasizes that the flaw exists in the file format parsing logic, making it essential for organizations to maintain updated security measures and monitoring systems to detect potential exploitation attempts.