CVE-2008-6928 in Complete Classifieds
Summary
by MITRE
Unrestricted file upload vulnerability in PHPStore Complete Classifieds allows remote authenticated users to execute arbitrary code by uploading a file with an executable extension as a logo, then accessing it via a direct request to the file in classifieds1/yellow_images/.
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Analysis
by VulDB Data Team • 11/10/2024
The vulnerability described in CVE-2008-6928 represents a critical security flaw in the PHPStore Complete Classifieds web application that enables remote authenticated attackers to achieve arbitrary code execution through unrestricted file upload capabilities. This issue stems from insufficient validation and sanitization of file uploads, specifically targeting the application's logo upload functionality. The vulnerability exists within the directory structure classifieds1/yellow_images/ where uploaded files are stored without proper restrictions on file types or extensions, creating an attack vector that can be exploited by malicious actors who have gained authentication credentials to the system.
The technical implementation of this vulnerability involves the application's failure to properly validate file extensions and content during the upload process. When an authenticated user uploads a file with an executable extension such as .php, .asp, or .jsp as a logo, the system accepts the upload without adequate security checks. This flaw aligns with CWE-434, which describes the weakness of unrestricted upload of executable code, and represents a classic case of insufficient input validation in web applications. The vulnerability specifically affects the file upload mechanism that handles logo images, allowing attackers to bypass normal security restrictions that should prevent execution of potentially malicious code within the web server's document root.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with a direct path to execute arbitrary code on the affected server. Once a malicious file is successfully uploaded and accessible via the web server, attackers can deploy web shells, backdoors, or other malicious payloads that can compromise the entire system. This vulnerability enables attackers to perform actions including but not limited to data exfiltration, privilege escalation, system reconnaissance, and persistent access to the compromised infrastructure. The attack requires only authenticated access to the application, which means that even a low-privilege user account can potentially exploit this vulnerability to gain elevated system access, making it particularly dangerous in environments where user accounts are not properly segmented or where default credentials are used.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements to prevent similar issues in the future. The primary immediate fix involves implementing strict file type validation that rejects executable extensions during the upload process and enforcing proper file extension checks that ensure only safe image formats such as jpg, png, or gif are accepted. Additionally, uploaded files should be stored outside the web root directory, and if they must be stored within the web accessible area, they should be renamed to prevent direct execution. This approach aligns with the principle of least privilege and defense in depth as outlined in various security frameworks including the NIST Cybersecurity Framework and ISO 27001 standards. Organizations should also implement proper access controls, regular security audits, and comprehensive input validation mechanisms to prevent similar unrestricted file upload vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1190 - Exploit Public-Facing Application, highlighting the need for proper application security controls and regular vulnerability assessments to prevent exploitation of such weaknesses.