Unrestricted File Upload in Online Examination & Learning Management System

Executive Summary

This vulnerability exists in the SourceCodester Online Examination & Learning Management System 1.0, specifically in the pathinfo function of the /upload_files.php file related to filename extension handling.

The flaw allows an attacker to manipulate the file upload process, resulting in unrestricted file uploads.

This means an attacker can remotely upload potentially malicious files without proper restrictions.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by checking for the presence of uploaded files with executable extensions (such as .php) in the uploads/class_docs/ directory, which should normally not contain executable scripts.

You can also look for suspicious HTTP POST requests to /upload_files.php that include file uploads, especially from instructor accounts or self-registered users.

Commands to help detect this include:

• On the server, list potentially malicious uploaded files: `find /path/to/uploads/class_docs/ -type f -name "*.php"`
• Check web server access logs for POST requests to /upload_files.php: `grep "/upload_files.php" /var/log/apache2/access.log | grep POST`
• Look for execution attempts of uploaded PHP files: `grep ".php" /var/log/apache2/access.log`

Useful 0 Not Useful 0

Impact Analysis

The vulnerability can lead to unauthorized remote file uploads, which may allow attackers to execute malicious code on the affected system.

This can compromise the integrity, confidentiality, and availability of the system and its data.

Potential impacts include system takeover, data breaches, defacement, or further exploitation within the network.

Useful 0 Not Useful 0

Compliance Impact

The vulnerability allows unrestricted file upload leading to remote code execution, which can result in unauthorized access and control over the affected system.

Such unauthorized access and potential data breaches could compromise the confidentiality, integrity, and availability of sensitive data, thereby negatively impacting compliance with standards and regulations like GDPR and HIPAA that require protection of personal and health information.

Specifically, the ability for an attacker to upload and execute malicious code could lead to exposure or manipulation of protected data, violating regulatory requirements for data security and breach prevention.

Useful 0 Not Useful 0

Mitigation Strategies

Immediate mitigation steps include:

• Implement an extension whitelist to allow only safe file types to be uploaded.
• Move uploaded files outside the web root directory to prevent direct web access.
• Use a proxy script to serve uploaded files instead of direct access.
• Add an .htaccess file in the uploads directory to disable PHP execution.
• Generate non-executable filenames for uploaded files.
• Validate MIME types server-side to ensure only allowed file types are accepted.

Useful 0 Not Useful 0