CVE-2005-2733 in Simple PHP Blog
Summary
by MITRE
upload_img_cgi.php in Simple PHP Blog (SPHPBlog) does not properly restrict file extensions of uploaded files, which could allow remote attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 11/23/2025
The vulnerability identified as CVE-2005-2733 resides within the upload_img_cgi.php component of Simple PHP Blog, a web-based blogging platform that was prevalent in the mid-2000s. This flaw represents a critical security oversight in the application's file upload validation mechanisms, creating a pathway for remote attackers to compromise the system through malicious file uploads. The vulnerability specifically targets the file extension validation process, which is a fundamental security control designed to prevent the execution of potentially harmful code on web servers.
The technical root cause of this vulnerability stems from inadequate input validation within the file upload functionality. The upload_img_cgi.php script fails to properly restrict or sanitize file extensions, allowing attackers to upload files with extensions that should be prohibited. This weakness enables attackers to upload malicious files such as php, asp, or other script files that could be executed on the web server. The flaw operates under CWE-434, which categorizes improper restriction of uploads of executable code, and aligns with ATT&CK technique T1190, which describes the use of compromised web applications for code execution. The vulnerability essentially bypasses the intended security controls that should prevent file type validation, creating a direct pathway for remote code execution.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete control over the affected web server. Once an attacker successfully uploads a malicious file, they can execute arbitrary code with the privileges of the web server process, potentially leading to full system compromise. This vulnerability allows for various attack vectors including web shell deployment, database access, and lateral movement within the network. The consequence extends beyond immediate code execution, as attackers can establish persistent access, exfiltrate sensitive data, or use the compromised server as a launchpad for further attacks against other systems. The vulnerability's impact is amplified by the fact that it requires no authentication, making it particularly dangerous for publicly accessible web applications.
Mitigation strategies for CVE-2005-2733 must address the core validation flaw through multiple layers of defense. Organizations should implement strict file type validation by maintaining a whitelist of allowed extensions rather than relying on blacklists, which are inherently vulnerable to bypass attempts. The system should also employ proper file content verification, ensuring that uploaded files match their claimed extensions through content analysis rather than just extension checking. Additionally, uploaded files should be stored in a separate directory from the web root with restricted permissions, and the web server should be configured to prevent execution of uploaded files. Security measures should include implementing proper access controls, regular security audits, and ensuring that all web applications are kept up to date with the latest security patches. Organizations should also consider deploying web application firewalls and intrusion detection systems to monitor for suspicious file upload activities, as this vulnerability represents a common attack vector that security tools can help detect and prevent.