Open Redirect in File Upload Handler

Executive Summary

This vulnerability involves a file-upload handler that redirects a user's browser to a URL taken from the Referer header without validation. An authenticated attacker can exploit this to redirect another user's browser to an arbitrary external site after a file upload completes.

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Detection Guidance

This vulnerability involves a file-upload handler redirecting browsers based on the Referer header without validation. To detect it, monitor HTTP requests for file uploads where the Referer header points to external domains. Check server logs for unusual redirect patterns after uploads. Use tools like Wireshark or tcpdump to inspect network traffic for suspicious redirect responses.

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Impact Analysis

This could allow attackers to trick users into visiting malicious sites, potentially leading to phishing attacks, credential theft, or malware downloads. Users may unknowingly expose sensitive data or fall victim to social engineering.

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Compliance Impact

This vulnerability may violate compliance requirements by exposing users to phishing or data theft risks, which could lead to unauthorized data access or breaches. Organizations may fail to meet security controls in GDPR or HIPAA if user redirection leads to data exposure.

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Mitigation Strategies

Immediately validate the Referer header against the application's trusted origins before processing file uploads. Implement strict allowlists for redirect URLs. Update server configurations to reject requests with untrusted Referer headers. Consider disabling automatic redirects after uploads entirely.

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