Performing SSL/TLS Security Assessment
Overview
Assess SSL/TLS server configurations using sslyze, a fast Python-based scanning library. This skill covers evaluating supported protocol versions (SSLv2/3, TLS 1.0-1.3), cipher suite strength, certificate chain validation, HSTS enforcement, OCSP stapling, and scanning for known vulnerabilities including Heartbleed, ROBOT, and session renegotiation weaknesses.
When to Use
- When conducting security assessments that involve performing ssl tls security assessment
- When following incident response procedures for related security events
- When performing scheduled security testing or auditing activities
- When validating security controls through hands-on testing
Most Often Missed & How to Confirm
- SNI and vhosts: scanning the IP without
-servername/SNI returns the default vhost's cert and ciphers, not the target's. Always set SNI (openssl s_client -connect host:443 -servername host; sslyze uses the hostname) or you assess the wrong service.
- Beyond 443: STARTTLS services (SMTP 25/587, IMAP 143, POP3 110, LDAP 389, FTPS, MySQL, PostgreSQL) need explicit STARTTLS probing —
testssl.sh --starttls smtp host:587. A 443-only scan misses them entirely.
- Full protocol/cipher matrix: don't stop at "TLS 1.2 supported" — enumerate SSLv2/SSLv3/TLS1.0/1.1 still enabled, weak ciphers (RC4, 3DES, EXPORT, NULL, CBC), and cipher order/forward secrecy. One accepted legacy protocol is the finding.
- Cert chain and trust: check the full chain order, intermediate completeness, expiry, SAN coverage, and signature algorithm. A leaf that validates in a browser may still ship an incomplete chain that breaks non-browser clients.
- Vuln checks need the precondition: Heartbleed needs the heartbeat extension; ROBOT needs RSA key exchange. Flag only after the specific check confirms it, never from version alone.
- How to confirm a hit: corroborate sslyze with
testssl.sh and a manual openssl s_client -cipher 'RC4' -tls1 handshake that actually completes — a completed handshake on a weak protocol/cipher is the proof; a lone scanner line is a candidate.
- Don't conclude "secure" until you've tested every TLS-bearing port, set SNI, and checked STARTTLS plus the legacy-protocol matrix.
Prerequisites
- Python 3.9+ with
sslyze library (pip install sslyze)
- Network access to target HTTPS servers on port 443
- Understanding of TLS protocol versions and cipher suite classifications
Steps
Step 1: Configure Server Scan
Create ServerScanRequest with ServerNetworkLocation specifying target hostname and port.
Step 2: Execute TLS Scan
Use sslyze Scanner to queue and execute scans for all TLS check commands concurrently.
Step 3: Analyze Results
Evaluate accepted cipher suites, certificate validity, protocol versions, and vulnerability scan results.
Step 4: Generate Security Report
Produce a JSON report with compliance findings and remediation recommendations.
Expected Output
JSON report with supported protocols, accepted cipher suites, certificate details, vulnerability results (Heartbleed, ROBOT), and HSTS status.
1---2name: performing-ssl-tls-security-assessment3description: Assess SSL/TLS server configurations using the sslyze Python library to evaluate cipher suites, certificate chains, protocol versions, HSTS headers, and known vulnerabilities like Heartbleed and ROBOT.4license: Apache-2.05---6# Performing SSL/TLS Security Assessment78## Overview910Assess SSL/TLS server configurations using sslyze, a fast Python-based scanning library. This skill covers evaluating supported protocol versions (SSLv2/3, TLS 1.0-1.3), cipher suite strength, certificate chain validation, HSTS enforcement, OCSP stapling, and scanning for known vulnerabilities including Heartbleed, ROBOT, and session renegotiation weaknesses.111213## When to Use1415- When conducting security assessments that involve performing ssl tls security assessment16- When following incident response procedures for related security events17- When performing scheduled security testing or auditing activities18- When validating security controls through hands-on testing1920## Most Often Missed & How to Confirm2122- **SNI and vhosts:** scanning the IP without `-servername`/SNI returns the default vhost's cert and ciphers, not the target's. Always set SNI (`openssl s_client -connect host:443 -servername host`; sslyze uses the hostname) or you assess the wrong service.23- **Beyond 443:** STARTTLS services (SMTP 25/587, IMAP 143, POP3 110, LDAP 389, FTPS, MySQL, PostgreSQL) need explicit STARTTLS probing — `testssl.sh --starttls smtp host:587`. A 443-only scan misses them entirely.24- **Full protocol/cipher matrix:** don't stop at "TLS 1.2 supported" — enumerate SSLv2/SSLv3/TLS1.0/1.1 still enabled, weak ciphers (RC4, 3DES, EXPORT, NULL, CBC), and cipher order/forward secrecy. One accepted legacy protocol is the finding.25- **Cert chain and trust:** check the *full* chain order, intermediate completeness, expiry, SAN coverage, and signature algorithm. A leaf that validates in a browser may still ship an incomplete chain that breaks non-browser clients.26- **Vuln checks need the precondition:** Heartbleed needs the heartbeat extension; ROBOT needs RSA key exchange. Flag only after the specific check confirms it, never from version alone.27- **How to confirm a hit:** corroborate sslyze with `testssl.sh` and a manual `openssl s_client -cipher 'RC4' -tls1` handshake that actually completes — a completed handshake on a weak protocol/cipher is the proof; a lone scanner line is a candidate.28- **Don't conclude "secure"** until you've tested every TLS-bearing port, set SNI, and checked STARTTLS plus the legacy-protocol matrix.2930## Prerequisites3132- Python 3.9+ with `sslyze` library (pip install sslyze)33- Network access to target HTTPS servers on port 44334- Understanding of TLS protocol versions and cipher suite classifications3536## Steps3738### Step 1: Configure Server Scan39Create ServerScanRequest with ServerNetworkLocation specifying target hostname and port.4041### Step 2: Execute TLS Scan42Use sslyze Scanner to queue and execute scans for all TLS check commands concurrently.4344### Step 3: Analyze Results45Evaluate accepted cipher suites, certificate validity, protocol versions, and vulnerability scan results.4647### Step 4: Generate Security Report48Produce a JSON report with compliance findings and remediation recommendations.4950## Expected Output5152JSON report with supported protocols, accepted cipher suites, certificate details, vulnerability results (Heartbleed, ROBOT), and HSTS status.
xalgord