CVE-2009-4817 in Ultimate Uploader
Summary
by MITRE
Unrestricted file upload vulnerability in Element-IT Ultimate Uploader 1.3 allows remote attackers to execute arbitrary code by uploading a file with an executable extension, then accessing it via a direct request to the file in upload/.
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Analysis
by VulDB Data Team • 09/14/2025
The CVE-2009-4817 vulnerability represents a critical unrestricted file upload flaw in Element-IT Ultimate Uploader version 1.3 that enables remote attackers to achieve arbitrary code execution through a straightforward yet dangerous exploitation vector. This vulnerability resides in the file upload functionality of the web application, where proper validation and sanitization of uploaded files are absent or insufficiently implemented. The flaw specifically allows attackers to bypass security restrictions by uploading files with executable extensions such as .asp, .aspx, .php, or .jsp, which can then be executed on the target server when accessed directly through the upload directory.
The technical nature of this vulnerability aligns with CWE-434, which describes "Unrestricted Upload of File with Dangerous Type," a well-documented weakness in web applications where the system fails to properly validate file types and extensions before storing uploaded content. The vulnerability operates at the application layer and can be exploited through a direct request to the uploaded file path within the upload/ directory, making it particularly dangerous as it does not require complex exploitation techniques or privilege escalation. Attackers can simply upload a malicious payload, such as a web shell or script, and then access it directly through the web server to execute arbitrary commands with the privileges of the web application user.
From an operational impact perspective, this vulnerability presents a severe threat to system security and data integrity. Once exploited, attackers gain the ability to execute arbitrary code on the target system, potentially leading to complete system compromise, data exfiltration, or establishment of persistent backdoors. The vulnerability is particularly concerning because it can be exploited remotely without authentication, making it accessible to any attacker with knowledge of the vulnerable application. The attack surface extends beyond simple code execution to include potential privilege escalation, lateral movement within networks, and the possibility of establishing a foothold for further attacks. According to ATT&CK framework, this vulnerability maps to T1190 - Exploit Public-Facing Application and T1059 - Command and Scripting Interpreter, as it enables remote exploitation of a public web application and allows execution of commands through uploaded malicious files.
The mitigation strategies for CVE-2009-4817 must address both immediate remediation and long-term prevention measures. Organizations should implement strict file type validation on the server-side, rejecting uploads of executable extensions and enforcing content-type checks. Proper input sanitization and file name sanitization are essential to prevent path traversal attacks and ensure uploaded files are stored in secure, non-executable directories. Additionally, web application firewalls should be configured to monitor and block suspicious file upload patterns and direct access attempts to upload directories. The most effective long-term solution involves updating to a patched version of Element-IT Ultimate Uploader or migrating to a more secure file upload solution that implements comprehensive validation and sanitization mechanisms. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other applications and ensure proper implementation of secure file upload practices.