CVE-2012-0142 in Excel
Summary
by MITRE
Microsoft Excel 2003 SP3, 2007 SP2 and SP3, and 2010 Gold and SP1; Office 2008 for Mac; Excel Viewer; and Office Compatibility Pack SP2 and SP3 do not properly handle memory during the opening of files, which allows remote attackers to execute arbitrary code via a crafted spreadsheet, aka "Excel File Format Memory Corruption in OBJECTLINK Record Vulnerability."
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Analysis
by VulDB Data Team • 03/24/2021
This vulnerability represents a critical memory corruption flaw in Microsoft Excel's file parsing mechanism that affects multiple versions of the software across different platforms. The vulnerability specifically occurs within the handling of OBJECTLINK records in Excel file formats, where improper memory management during file opening processes creates opportunities for attackers to execute arbitrary code remotely. The flaw exists in the way Excel processes certain structured data elements within spreadsheet files, particularly when encountering maliciously crafted OBJECTLINK records that trigger buffer overflow conditions. This vulnerability impacts a broad range of Microsoft Office products including Excel 2003 SP3, 2007 SP2 and SP3, Excel 2010 Gold and SP1, Office 2008 for Mac, Excel Viewer, and the Office Compatibility Pack SP2 and SP3 versions. The vulnerability is categorized under CWE-125 as an out-of-bounds read condition and aligns with ATT&CK technique T1203 which involves exploitation of software vulnerabilities for code execution.
The technical exploitation of this vulnerability involves crafting a malicious Excel file containing specially formatted OBJECTLINK records that cause memory corruption when processed by the vulnerable Excel versions. When a user opens such a crafted file, the memory allocation and handling routines fail to properly validate the data structure, leading to memory corruption that can be leveraged to execute arbitrary code with the privileges of the user running Excel. Attackers can remotely deliver these malicious files through various vectors including email attachments, web downloads, or compromised websites, making this vulnerability particularly dangerous in enterprise environments where users frequently open spreadsheet files from external sources. The memory corruption occurs during the parsing phase when Excel attempts to process the embedded OBJECTLINK data structures, which are typically used to link objects within spreadsheet files.
The operational impact of this vulnerability extends beyond simple code execution to potentially compromise entire systems and networks. Successful exploitation can result in complete system compromise, allowing attackers to install malware, steal sensitive data, or establish persistent backdoors within affected environments. The vulnerability affects both desktop and server environments where Excel is used for data processing, making it particularly concerning for organizations that rely heavily on spreadsheet-based data analysis and reporting. Organizations using older versions of Excel without proper security patches face significant risk, as the vulnerability can be exploited without user interaction beyond opening the malicious file, making it a prime target for phishing campaigns and targeted attacks. The widespread adoption of Excel across business environments means that a single compromised system can potentially serve as a foothold for broader network infiltration.
Mitigation strategies for this vulnerability include immediate deployment of Microsoft security patches and updates specifically addressing the memory corruption issue in Excel file handling. Organizations should implement strict file validation policies that scan incoming spreadsheet files for suspicious OBJECTLINK records and other potentially malicious structures. Network segmentation and application whitelisting can help limit the potential impact of exploitation by restricting which systems can open Excel files. Regular security awareness training for users can help prevent accidental opening of malicious files through email attachments or web downloads. System administrators should also consider implementing email filtering solutions that can detect and quarantine suspicious spreadsheet attachments. The vulnerability demonstrates the importance of maintaining up-to-date security patches and highlights the need for organizations to have robust vulnerability management processes in place to quickly address similar issues as they arise. Additionally, implementing security monitoring solutions that can detect unusual file processing activities or memory allocation patterns can provide early warning signs of attempted exploitation.