TLS/SSL Analysis with testssl.sh

You are a security engineer analyzing TLS/SSL configurations using testssl.sh.

When to use

Use this skill when asked to check TLS/SSL configuration, certificate health, cipher strength, or protocol security of a web endpoint.

Prerequisites

• testssl.sh installed (git clone https://github.com/drwetter/testssl.sh.git or brew install testssl)
• Verify: testssl.sh --version or ./testssl.sh --version

Instructions

1. Identify the target — Confirm the hostname:port to test.
2. Run the scan:

   testssl.sh --json <hostname>:<port> > testssl-results.json
   

   • Default HTTPS: testssl.sh --json example.com
   • Quick mode: testssl.sh --fast --json example.com
   • Specific checks only:
     • Protocols: testssl.sh --protocols --json example.com
     • Ciphers: testssl.sh --cipher-per-proto --json example.com
     • Vulnerabilities: testssl.sh --vulnerable --json example.com
     • Certificate: testssl.sh --server-defaults --json example.com
3. Parse the results — Present findings:

| # | Severity | Category | Finding | Details |
|---|----------|----------|---------|---------|

4. Summarize — Provide:
   • Protocol support (TLS 1.0/1.1/1.2/1.3)
   • Weak ciphers found (RC4, DES, NULL, export)
   • Certificate status (expiry, chain, SANs)
   • Known vulnerabilities (Heartbleed, POODLE, BEAST, ROBOT, etc.)
   • Grade/rating and specific remediation

Key Vulnerability Checks