Insecure transition from HTTP to HTTPS in form post
Description
This vulnerability occurs when a web form is served over an unencrypted HTTP connection but submits data to an HTTPS endpoint. While the form action points to a secure URL, the initial page delivery over HTTP creates a critical security gap. An attacker performing a man-in-the-middle (MITM) attack can intercept the HTTP response and modify the form's action attribute to redirect submitted data to a malicious server, completely bypassing the intended HTTPS protection.
Remediation
Serve all pages containing forms that handle sensitive data exclusively over HTTPS. This ensures the entire user interaction, from initial page load to form submission, is encrypted and protected from tampering.
Implementation steps:
1. Configure your web server to redirect all HTTP requests to HTTPS
2. Update all internal links and form pages to use HTTPS URLs
3. Implement HTTP Strict Transport Security (HSTS) headers to prevent protocol downgrade attacks
4. Ensure valid SSL/TLS certificates are properly configured
Example server-side redirect configuration (Apache):
<VirtualHost *:80> ServerName example.com Redirect permanent / https://example.com/ </VirtualHost>
Example HSTS header configuration:
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
Additionally, review all application pages to ensure no mixed content warnings occur and that all resources (scripts, stylesheets, images) are also loaded over HTTPS.