Senior Security Engineer

Security engineering tools for threat modeling, vulnerability analysis, secure architecture design, and penetration testing.

Table of Contents

• Threat Modeling Workflow
• Security Architecture Workflow
• Vulnerability Assessment Workflow
• Secure Code Review Workflow
• Incident Response Workflow
• Security Tools Reference
• Tools and References

Threat Modeling Workflow

Identify and analyze security threats using STRIDE methodology.

Workflow: Conduct Threat Model

1. Define system scope and boundaries:
   • Identify assets to protect
   • Map trust boundaries
   • Document data flows
2. Create data flow diagram:
   • External entities (users, services)
   • Processes (application components)
   • Data stores (databases, caches)
   • Data flows (APIs, network connections)
3. Apply STRIDE to each DFD element (see STRIDE per Element Matrix below)
4. Score risks using DREAD:
   • Damage potential (1-10)
   • Reproducibility (1-10)
   • Exploitability (1-10)
   • Affected users (1-10)
   • Discoverability (1-10)
5. Prioritize threats by risk score
6. Define mitigations for each threat
7. Document in threat model report
8. Validation: All DFD elements analyzed; STRIDE applied; threats scored; mitigations mapped

STRIDE Threat Categories

STRIDE per Element Matrix

See: references/threat-modeling-guide.md

Security Architecture Workflow

Design secure systems using defense-in-depth principles.

Workflow: Design Secure Architecture

1. Define security requirements:
   • Compliance requirements (GDPR, HIPAA, PCI-DSS)
   • Data classification (public, internal, confidential, restricted)
   • Threat model inputs
2. Apply defense-in-depth layers:
   • Perimeter: WAF, DDoS protection, rate limiting
   • Network: Segmentation, IDS/IPS, mTLS
   • Host: Patching, EDR, hardening
   • Application: Input validation, authentication, secure coding
   • Data: Encryption at rest and in transit
3. Implement Zero Trust principles:
   • Verify explicitly (every request)
   • Least privilege access (JIT/JEA)
   • Assume breach (segment, monitor)
4. Configure authentication and authorization:
   • Identity provider selection
   • MFA requirements
   • RBAC/ABAC model
5. Design encryption strategy:
   • Key management approach
   • Algorithm selection
   • Certificate lifecycle
6. Plan security monitoring:
   • Log aggregation
   • SIEM integration
   • Alerting rules
7. Document architecture decisions
8. Validation: Defense-in-depth layers defined; Zero Trust applied; encryption strategy documented; monitoring planned

Defense-in-Depth Layers

Layer 1: PERIMETER
  WAF, DDoS mitigation, DNS filtering, rate limiting

Layer 2: NETWORK
  Segmentation, IDS/IPS, network monitoring, VPN, mTLS

Layer 3: HOST
  Endpoint protection, OS hardening, patching, logging

Layer 4: APPLICATION
  Input validation, authentication, secure coding, SAST

Layer 5: DATA
  Encryption at rest/transit, access controls, DLP, backup

Authentication Pattern Selection

See: references/security-architecture-patterns.md

Vulnerability Assessment Workflow

Identify and remediate security vulnerabilities in applications.

Workflow: Conduct Vulnerability Assessment

1. Define assessment scope:
   • In-scope systems and applications
   • Testing methodology (black box, gray box, white box)
   • Rules of engagement
2. Gather information:
   • Technology stack inventory
   • Architecture documentation
   • Previous vulnerability reports
3. Perform automated scanning:
   • SAST (static analysis)
   • DAST (dynamic analysis)
   • Dependency scanning
   • Secret detection
4. Conduct manual testing:
   • Business logic flaws
   • Authentication bypass
   • Authorization issues
   • Injection vulnerabilities
5. Classify findings by severity:
   • Critical: Immediate exploitation risk
   • High: Significant impact, easier to exploit
   • Medium: Moderate impact or difficulty
   • Low: Minor impact
6. Develop remediation plan:
   • Prioritize by risk
   • Assign owners
   • Set deadlines
7. Verify fixes and document
8. Validation: Scope defined; automated and manual testing complete; findings classified; remediation tracked

For OWASP Top 10 vulnerability descriptions and testing guidance, refer to owasp.org/Top10.

Vulnerability Severity Matrix

Secure Code Review Workflow

Review code for security vulnerabilities before deployment.

Workflow: Conduct Security Code Review

1. Establish review scope:
   • Changed files and functions
   • Security-sensitive areas (auth, crypto, input handling)
   • Third-party integrations
2. Run automated analysis:
   • SAST tools (Semgrep, CodeQL, Bandit)
   • Secret scanning
   • Dependency vulnerability check
3. Review authentication code:
   • Password handling (hashing, storage)
   • Session management
   • Token validation
4. Review authorization code:
   • Access control checks
   • RBAC implementation
   • Privilege boundaries
5. Review data handling:
   • Input validation
   • Output encoding
   • SQL query construction
   • File path handling
6. Review cryptographic code:
   • Algorithm selection
   • Key management
   • Random number generation
7. Document findings with severity
8. Validation: Automated scans passed; auth/authz reviewed; data handling checked; crypto verified; findings documented

Security Code Review Checklist

Secure vs Insecure Patterns

| Pattern | Issue | Secure Alternative | |---------|------