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Certificate Transparency Logs

  • SSL/TLS encrypts commz between a browser and a website
  • It uses a digital certificate to verify the websites identity and then allows commz
  • Attackers can exploit rogue or misissued certs to impersonate websites, intercept sensitive data, spread malware
  • CT Logs are important in this case

CT Logs:

  • public append-only ledgers that record the issuance of SSL/TLS certs
  • When a CA (Cert Authority) issues a new certificate, it is sent to multiple CT Logs which are maintained by independent organizations and can be inspected by anyone.
  • Global Registry of Certs
  • Early Detection of Rogue Certificates
  • Accountability for Certificate Authorities
  • Strengthening the Web PKI

Web Recon:

  • CT Logs for subdomain enum are better than wordlist brute-forcing as they can provide a complete list of the domains and subdomains issued.
  • They can also unveil subdomains associated with old or expired certs. These might have old software and vulns that can be exploited.

Tools:

  • crt.sh
  • censys
  • curl -s "https://crt.sh/?q=facebook.com&output=json" | jq -r '.[] | select(.name_value | contains("dev")) | .name_value' | sort -u