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TLS Analysis Component ​

The TLS analysis component (internal/tlsinfo) provides secure TLS certificate inspection and analysis for domain security mapping.

Overview ​

The TLS analysis component establishes secure connections to domains and extracts certificate metadata, enabling SPYDER to map TLS infrastructure relationships and certificate usage patterns across domains.

Core Function ​

FetchCert(host string) (*emit.NodeCert, error) ​

Establishes a TLS connection and extracts certificate information from the presented certificate chain.

Parameters:

  • host: The domain name to connect to for certificate inspection

Returns:

  • *emit.NodeCert: Certificate node containing metadata, or nil if no certificate
  • error: Connection or parsing error, if any

TLS Connection Process ​

Secure Connection Establishment ​

  1. TLS Dialer Configuration: Uses tls.Dialer with proper ServerName indication (SNI)
  2. Connection Target: Connects to host on port 443 (HTTPS)
  3. Timeout Control: 8-second connection timeout for responsiveness
  4. Certificate Extraction: Retrieves leaf certificate from peer chain

Certificate Analysis ​

  • Subject Public Key Info (SPKI) Hashing: SHA-256 hash of the certificate's public key
  • Common Name Extraction: Subject and Issuer Common Names
  • Validity Period: Certificate not-before and not-after timestamps
  • Base64 Encoding: SPKI hash encoded for JSON serialization

Certificate Node Structure ​

emit.NodeCert Fields ​

go
type NodeCert struct {
    SPKI      string    `json:"spki_sha256"`    // Base64-encoded SHA-256 of SPKI
    SubjectCN string    `json:"subject_cn"`     // Certificate subject common name
    IssuerCN  string    `json:"issuer_cn"`      // Certificate issuer common name
    NotBefore time.Time `json:"not_before"`     // Certificate valid from date
    NotAfter  time.Time `json:"not_after"`      // Certificate valid until date
}

SPKI Hash Generation ​

  • Algorithm: SHA-256 of RawSubjectPublicKeyInfo
  • Encoding: Base64 standard encoding
  • Purpose: Unique certificate identification and relationship mapping

Edge Creation ​

TLS certificate analysis creates USES_CERT edges:

  • Source: Domain name (host)
  • Target: Certificate SPKI hash
  • Purpose: Map which domains use which certificates

Security Features ​

Certificate Verification ​

  • SNI Support: Proper Server Name Indication for virtual hosting
  • Certificate Chain: Analyzes presented certificate chain
  • Leaf Certificate Focus: Extracts data from the leaf (end-entity) certificate

Connection Security ​

  • Standard TLS: Uses Go's standard TLS implementation
  • Secure Defaults: Relies on system certificate verification policies
  • Timeout Protection: Prevents hanging on unresponsive servers

Error Handling ​

Connection Errors ​

  • Network Unreachable: Host not accessible on port 443
  • TLS Handshake Failure: Invalid certificate or TLS configuration
  • Timeout: Connection establishment exceeds 8-second limit
  • DNS Resolution: Host name resolution failures

Certificate Errors ​

  • Missing Certificate: Server presents no certificate (returns nil)
  • Empty Chain: Peer certificates list is empty
  • Invalid Certificate: Malformed certificate data

Integration Points ​

Probe Pipeline Integration ​

  1. Input: Domain names from the processing queue
  2. Processing: TLS connection and certificate analysis
  3. Output: Certificate nodes and USES_CERT edges

Deduplication Integration ​

  • SPKI hashes serve as unique certificate identifiers
  • Multiple domains using the same certificate share the same SPKI
  • Efficient deduplication of certificate data

Performance Considerations ​

Connection Management ​

  • Individual Connections: Each certificate fetch uses a new connection
  • Timeout Control: 8-second limit prevents slow connections from blocking pipeline
  • Context Cancellation: Supports graceful shutdown

Resource Usage ​

  • Memory Efficient: Extracts only necessary certificate metadata
  • No Certificate Storage: Does not store full certificate data
  • Hash-Based Identification: Compact certificate fingerprinting

Common Use Cases ​

Certificate Mapping ​

  • Shared Certificates: Identify domains using the same TLS certificate
  • CDN Detection: Map Content Delivery Network certificate usage
  • Certificate Authority Analysis: Track issuer relationships

Security Analysis ​

  • Certificate Validity: Monitor certificate expiration dates
  • Subject Analysis: Identify certificate subject patterns
  • Issuer Tracking: Map Certificate Authority relationships

Infrastructure Discovery ​

  • Load Balancer Detection: Identify shared certificate infrastructure
  • Hosting Provider Analysis: Map hosting service certificate patterns
  • Multi-Domain Certificates: Discover SAN certificate usage

Configuration Considerations ​

Network Configuration ​

  • Firewall Rules: Ensure outbound HTTPS (port 443) connectivity
  • Proxy Settings: Configure for environments requiring HTTP proxies
  • DNS Resolution: Reliable DNS resolution required for host connections

TLS Configuration ​

  • Certificate Verification: Uses system certificate store for verification
  • Protocol Versions: Supports modern TLS protocol versions
  • Cipher Suites: Uses Go's secure default cipher suite selection

Monitoring Metrics ​

TLS analysis generates metrics for:

  • Connection Success Rate: Percentage of successful TLS connections
  • Certificate Extraction Rate: Rate of valid certificate retrieval
  • Connection Latency: Time to establish TLS connection and extract certificate
  • Error Classification: Types and frequency of TLS/certificate errors

Security Considerations ​

Certificate Validation ​

  • Chain Verification: Validates certificate chain integrity
  • Expiration Checks: Identifies expired or soon-to-expire certificates
  • Revocation Status: Uses system-level revocation checking

Privacy and Compliance ​

  • No Certificate Storage: Only metadata extracted and stored
  • SPKI Fingerprinting: Certificates identified by public key hash
  • No Private Key Access: Only public certificate information accessed

Troubleshooting ​

Common Issues ​

  • Port 443 Blocked: Firewall or network policy blocking HTTPS
  • SNI Issues: Server not properly configured for virtual hosting
  • Certificate Errors: Invalid, expired, or self-signed certificates
  • Timeout Issues: Slow servers or network connectivity problems

Debugging Steps ​

  1. Network Connectivity: Verify host reachability on port 443
  2. Manual TLS Test: Use openssl s_client to test TLS connectivity
  3. Certificate Inspection: Examine certificate chain manually
  4. DNS Resolution: Verify hostname resolves correctly