SSL Secure renegotiation is not supported
Description
The server does not support secure renegotiation, making it vulnerable to CVE-2009-3555. This vulnerability affects TLS and SSL 3.0 implementations that fail to properly associate renegotiation handshakes with existing connections. Attackers positioned between the client and server can exploit this flaw to inject unauthorized requests into established HTTPS sessions before renegotiation completes. The injected data is processed by the server as if it came from the authenticated client, enabling plaintext injection attacks.
Remediation
- Enable Secure Renegotiation: Update SSL/TLS libraries and server software to versions that support RFC 5746 secure renegotiation. For OpenSSL, upgrade to version 0.9.8l or later. For Apache mod_ssl, upgrade to version 2.2.15 or later.
- Verify Secure Renegotiation Support: Test your server configuration to confirm secure renegotiation is enabled. Use OpenSSL command-line tools to verify:
openssl s_client -connect yourserver.com:443 -reconnect
Look for "Secure Renegotiation IS supported" in the output. - Disable Insecure Renegotiation (Temporary Mitigation): If immediate patching is not possible, disable client-initiated renegotiation entirely. For Apache with mod_ssl, add:
SSLInsecureRenegotiation off
For Nginx, renegotiation is disabled by default in modern versions. For OpenSSL-based applications, set:SSL_OP_NO_RENEGOTIATION
- Configure Strong Cipher Suites: Ensure your server uses modern, secure cipher suites and disable deprecated protocols (SSLv2, SSLv3, TLS 1.0). Prioritize TLS 1.2 and TLS 1.3 where supported.
- Implement Defense in Depth: Deploy additional security controls including Web Application Firewalls (WAF), intrusion detection systems, and regular security monitoring to detect potential exploitation attempts.
- Regular Security Audits: Periodically scan your infrastructure for SSL/TLS vulnerabilities using tools like SSL Labs' SSL Server Test or nmap with ssl-enum-ciphers script.