CVE-2005-3765 in Exponent
Summary
by MITRE
Exponent CMS 0.96.3 and later versions performs a chmod on uploaded files to give them execute permissions, which allows remote attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 06/12/2019
The vulnerability identified as CVE-2005-3765 affects Exponent CMS versions 0.96.3 and later, presenting a critical security flaw that enables remote code execution through improper file permission handling. This vulnerability stems from the content management system's automatic chmod operation performed on uploaded files, which inadvertently grants execute permissions to uploaded content. The flaw represents a classic case of insufficient input validation and improper privilege management, allowing malicious actors to upload potentially harmful files and subsequently execute them on the target system. The vulnerability exists within the file upload processing mechanism where the system automatically sets execute permissions without proper sanitization or authorization checks, creating an attack vector that directly violates secure coding principles.
The technical implementation of this vulnerability involves the CMS's file handling routines that automatically apply execute permissions to all uploaded files through chmod operations. When users upload files through the CMS interface, the system processes these uploads and applies execute permissions regardless of file type or intended use. This behavior creates a privilege escalation scenario where any authenticated user can upload a malicious file such as a shell script or binary payload and then execute it on the server. The vulnerability is particularly dangerous because it operates at the filesystem level, bypassing many traditional web application security controls and directly leveraging the operating system's permission model. This flaw aligns with CWE-732, which addresses improper permission assignment, and represents a direct violation of the principle of least privilege in system design.
The operational impact of this vulnerability is severe and far-reaching, as it provides remote attackers with complete control over the affected system. Once exploited, attackers can execute arbitrary code with the privileges of the web server process, potentially leading to full system compromise, data exfiltration, or use as a foothold for further attacks within the network. The vulnerability affects the integrity and confidentiality of the entire CMS installation, as any uploaded file can become an execution point. Attackers can leverage this to establish persistent backdoors, install malware, or perform reconnaissance activities. The impact extends beyond immediate system compromise to include potential data loss, service disruption, and regulatory compliance violations, particularly in environments where the CMS handles sensitive information. This vulnerability also demonstrates weaknesses in the application's security architecture and highlights the importance of proper file handling and access control mechanisms.
Mitigation strategies for this vulnerability require immediate action to address the root cause through code-level fixes and operational security improvements. The primary solution involves modifying the CMS code to remove automatic execute permission assignment during file uploads, implementing proper file type validation, and ensuring that only authorized file types receive execute permissions. Organizations should also implement strict file upload restrictions, including MIME type validation, file extension filtering, and content analysis to prevent malicious file uploads. Network-level protections such as web application firewalls should be deployed to monitor and block suspicious upload activities, while proper access controls and privilege separation should be enforced to limit the damage potential. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in the system's architecture. The remediation process should follow established security frameworks and guidelines, including the implementation of secure coding practices that align with industry standards such as those recommended by the Open Web Application Security Project and the Center for Internet Security. Additionally, system administrators should implement monitoring and alerting mechanisms to detect unauthorized file upload activities and execute permission changes, ensuring rapid response to potential exploitation attempts.