CVE-2006-3281 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6.0 does not properly handle Drag and Drop events, which allows remote user-assisted attackers to execute arbitrary code via a link to an SMB file share with a filename that contains encoded ..\ (%2e%2e%5c) sequences and whose extension contains the CLSID Key identifier for HTML Applications (HTA), aka "Folder GUID Code Execution Vulnerability." NOTE: directory traversal sequences were used in the original exploit, although their role is not clear.
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Analysis
by VulDB Data Team • 06/21/2025
The vulnerability described in CVE-2006-3281 represents a critical security flaw in Microsoft Internet Explorer 6.0 that exploits improper handling of drag and drop operations within the browser's file system navigation mechanisms. This issue specifically targets the way Internet Explorer processes file paths when users interact with file shares through drag and drop functionality, creating a pathway for remote attackers to execute arbitrary code on vulnerable systems. The vulnerability operates through a sophisticated attack vector that combines file system traversal techniques with HTML Application (HTA) execution capabilities, making it particularly dangerous for enterprise environments where users may inadvertently interact with malicious file shares.
The technical implementation of this vulnerability relies on exploiting the browser's insufficient validation of file paths during drag and drop operations, particularly when dealing with SMB file shares. Attackers craft malicious file names containing encoded directory traversal sequences using the pattern %2e%2e%5c which translates to ..\ in URL encoded format. When combined with HTA file extensions that contain CLSID Key identifiers, these sequences allow the attacker to bypass normal file system restrictions and execute malicious code. This flaw is categorized under CWE-22 as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" and specifically manifests as a code execution vulnerability through improper handling of user input in file system operations. The attack requires user interaction through a malicious link that prompts the user to drag and drop a file from an SMB share, making it a user-assisted remote code execution vulnerability.
The operational impact of this vulnerability extends beyond simple code execution, as it represents a significant threat to enterprise security infrastructure where users frequently access network file shares. When exploited, the vulnerability allows attackers to execute arbitrary code with the privileges of the user running Internet Explorer, potentially leading to complete system compromise. The attack vector is particularly concerning because it leverages legitimate browser functionality to deliver malicious payloads, making detection more difficult for traditional security measures. Organizations running Internet Explorer 6.0 were particularly vulnerable as this version lacked proper input validation for file paths during drag and drop operations, and the vulnerability could be exploited through web-based attacks that required no local privileges or special tools beyond crafting the malicious file names. This vulnerability aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1203 for "Exploitation for Client Execution" as it enables attackers to execute malicious code through browser-based interactions.
Mitigation strategies for CVE-2006-3281 focused on both immediate remediation and long-term security hardening measures. Microsoft released security patches that addressed the core issue in Internet Explorer 6.0, but organizations also implemented network-level controls to restrict access to SMB shares and disable drag and drop functionality in browser environments where it was not essential. Security configurations were adjusted to prevent automatic execution of HTA files and to enforce strict path validation for file system operations. Additional protective measures included user education about the risks of drag and drop operations with unknown file sources, network segmentation to isolate file shares, and implementation of web application firewalls to detect and block malicious URL patterns. Organizations should have also considered disabling the affected browser functionality entirely or upgrading to newer versions of Internet Explorer that contained proper input validation for file path operations. The vulnerability highlighted the importance of proper input validation and the need for security controls that address both client-side and server-side file access operations, as well as the critical role of user awareness in preventing exploitation of browser-based vulnerabilities.