CVE-2011-1274 in Excel
Summary
by MITRE
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 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 Array Access Vulnerability."
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Analysis
by VulDB Data Team • 11/09/2021
The vulnerability identified as CVE-2011-1274 represents a critical memory corruption flaw within Microsoft Excel's file parsing mechanisms that affects multiple versions across different platforms including Windows and Mac operating systems. This vulnerability specifically manifests during the processing of Excel spreadsheet files where the application fails to properly validate record information contained within the file structure, creating an exploitable condition that can be leveraged by malicious actors to gain unauthorized system access or disrupt normal operations.
The technical nature of this vulnerability stems from an out-of-bounds array access condition that occurs when Excel attempts to parse malformed or specially crafted spreadsheet files. When the application encounters record structures that exceed expected boundaries or contain invalid data patterns, it fails to implement proper bounds checking mechanisms during the parsing process. This flaw falls under the CWE-129 category of "Improper Validation of Array Index" and represents a classic buffer overflow scenario where the application accesses memory locations beyond the allocated array boundaries. The vulnerability is particularly dangerous because it can be triggered through legitimate file processing operations, making it difficult to distinguish between benign and malicious file interactions.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass full system compromise capabilities. Remote attackers can exploit this weakness by crafting malicious Excel files that, when opened by an affected system, trigger memory corruption that can be leveraged to execute arbitrary code with the privileges of the affected user. The vulnerability affects a wide range of Microsoft Office products including Excel 2002 SP3, 2003 SP3, 2007 SP2, 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 broad impact surface makes the vulnerability particularly concerning for enterprise environments where multiple Office versions may coexist.
From an attack perspective, this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to initial access through malicious file delivery and privilege escalation through code execution. The attack vector typically involves social engineering campaigns where users are tricked into opening malicious Excel files, often delivered via email attachments or compromised websites. The vulnerability's exploitation capability places it in the category of remote code execution vulnerabilities that can be used to establish persistent access to target systems. Security researchers have noted that the exploitation of this vulnerability often requires a user interaction component, making user education and awareness critical defensive measures.
Mitigation strategies for CVE-2011-1274 should encompass both immediate patch management and defensive operational measures. Microsoft released security updates to address this vulnerability, and organizations should prioritize applying these patches across all affected systems. Additionally, implementing file validation controls, restricting Excel file handling in high-security environments, and deploying email filtering solutions that can detect and quarantine potentially malicious Office files can significantly reduce the risk of exploitation. Network segmentation and user access controls should be enforced to limit the potential impact of successful exploitation attempts. Organizations should also consider implementing application whitelisting policies that restrict execution of Office applications to trusted sources only, as this approach can prevent unauthorized code execution even if the vulnerability is exploited. The vulnerability serves as a reminder of the critical importance of proper input validation and bounds checking in software development practices, particularly for applications that process untrusted data from external sources.