CVE-2011-1273 in Excel
Summary
by MITRE
Microsoft Excel 2002 SP3, 2003 SP3, 2007 SP2, and 2010; Office 2004, 2008, and 2011 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 Improper Record Parsing Vulnerability."
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Analysis
by VulDB Data Team • 11/09/2021
The vulnerability identified as CVE-2011-1273 represents a critical flaw in Microsoft Excel's file parsing mechanism that affects multiple versions across different platforms including Windows and Mac operating systems. This issue stems from insufficient validation of record information during the parsing process of excel spreadsheet files, creating a pathway for malicious actors to exploit the software through carefully crafted malicious files. The vulnerability specifically targets the way Excel handles structured data records within spreadsheet files, where the application fails to properly validate the integrity and boundaries of these records before processing them, leading to potential memory corruption issues.
The technical nature of this vulnerability places it under CWE-125, which describes "Out-of-bounds Read" conditions where applications read data beyond the intended boundaries of allocated buffers. Attackers can exploit this weakness by creating specially crafted excel files that contain malformed or oversized record structures designed to trigger memory corruption when processed by vulnerable Excel versions. The flaw operates at the parsing layer of the application, where Excel's internal file format handler does not adequately verify the length and structure of records before attempting to parse them, allowing attackers to manipulate memory layout and potentially execute arbitrary code with the privileges of the user running the application. This type of vulnerability falls under the ATT&CK technique T1203, which involves exploitation of software vulnerabilities to gain code execution capabilities.
The operational impact of CVE-2011-1273 extends beyond simple denial of service scenarios, as successful exploitation can result in complete system compromise through remote code execution. When an unsuspecting user opens a maliciously crafted spreadsheet file, the vulnerable Excel application becomes susceptible to memory corruption that can be leveraged to inject and execute malicious code within the user's session context. This creates a significant risk for enterprise environments where users may encounter such malicious files through email attachments, web downloads, or file sharing mechanisms, potentially leading to data breaches, system infiltration, or deployment of additional malware. The vulnerability affects a broad range of Microsoft Office products, making it particularly dangerous as attackers can target users across different platforms and versions.
Mitigation strategies for this vulnerability require immediate patching of affected systems with the appropriate Microsoft security updates, as the original vulnerability was addressed through official security releases. Organizations should implement comprehensive patch management procedures to ensure all vulnerable Excel installations receive the necessary updates promptly. Additionally, administrative controls should include restricting user access to potentially harmful file types through email filtering, web proxy configurations, and file type restrictions in enterprise environments. Network monitoring and endpoint protection solutions should be configured to detect and block suspicious file access patterns that may indicate exploitation attempts. Security awareness training for users should emphasize the importance of avoiding suspicious email attachments and untrusted file downloads. The vulnerability also highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that include multiple layers of protection to prevent successful exploitation attempts.