CVE-2006-3867 in Excel
Summary
by MITRE
Unspecified vulnerability in Microsoft Excel 2000, 2002, 2003, 2004 for Mac, v.X for Mac, and Excel Viewer 2003 allows user-assisted attackers to execute arbitrary code via a crafted Lotus 1-2-3 file, a different vulnerability than CVE-2006-2387 and CVE-2006-3875.
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Analysis
by VulDB Data Team • 04/24/2026
This vulnerability represents a critical code execution flaw in multiple versions of Microsoft Excel for Mac operating systems including Excel 2000, 2002, 2003, 2004, and v.X for Mac, as well as Excel Viewer 2003. The vulnerability specifically arises when processing maliciously crafted Lotus 1-2-3 files, which demonstrates a dangerous cross-format exploitation vector that leverages the interoperability features between different spreadsheet applications. The vulnerability is classified as user-assisted, meaning that successful exploitation requires some form of social engineering or user interaction, typically involving the opening of a malicious file that has been disguised as legitimate content. This characteristic places the vulnerability in the category of attack vectors that rely on user behavior modification, making it particularly challenging to defend against through automated means alone.
The technical implementation of this vulnerability stems from inadequate input validation and memory handling within Excel's file parsing routines when processing Lotus 1-2-3 format files. When Excel encounters a malformed or maliciously constructed 1-2-3 file, the application fails to properly validate the file structure and data offsets, leading to potential buffer overflows or memory corruption conditions. This type of vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read conditions that can lead to arbitrary code execution. The memory corruption occurs during the parsing process where Excel attempts to convert or import data from the legacy 1-2-3 format into its own internal data structures, creating opportunities for attackers to inject malicious code that executes with the privileges of the user running Excel.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a pathway to establish persistent access to affected systems. Since the vulnerability requires user interaction to trigger, attackers typically employ social engineering tactics to convince victims to open malicious files, often through email attachments or malicious downloads. This user-assisted nature means that the attack surface is broader than purely automated exploits, as it requires human factors to be leveraged. The vulnerability affects a wide range of Excel versions across different Mac operating system releases, making it particularly dangerous in enterprise environments where multiple versions might coexist. The attack vector operates through the file import functionality, which is commonly used in business environments where users regularly open files from external sources, creating numerous potential entry points for exploitation.
Mitigation strategies for this vulnerability should focus on multiple defensive layers to protect against both automated and social engineering attacks. Organizations should implement strict file validation policies that prevent automatic execution of potentially malicious files, particularly those originating from untrusted sources. The most effective immediate mitigation involves disabling the automatic import of Lotus 1-2-3 files within Excel applications, which can be achieved through registry modifications or configuration settings that prevent the application from processing these formats. Additionally, user education and awareness programs should be implemented to help users recognize suspicious email attachments or downloads that might contain malicious files. System administrators should also consider implementing application whitelisting policies that restrict which applications can be executed on the system, thereby limiting the potential impact of successful exploitation attempts. The vulnerability also highlights the importance of keeping software updated, as Microsoft would have addressed this issue in subsequent security updates, making it crucial for organizations to maintain current security patches and updates for all Microsoft Office applications. This vulnerability demonstrates how legacy file format support can create unexpected security risks and underscores the need for regular security assessments of all software components that handle external data inputs, particularly those with complex file parsing capabilities.