neekware/artifacts/bundle/skills/engineering-team/senior-security

Senior Security Engineer

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

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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

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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

| Category | Security Property | Mitigation Focus | | ---------------------- | ----------------- | ------------------------------ | | Spoofing | Authentication | MFA, certificates, strong auth | | Tampering | Integrity | Signing, checksums, validation | | Repudiation | Non-repudiation | Audit logs, digital signatures | | Information Disclosure | Confidentiality | Encryption, access controls | | Denial of Service | Availability | Rate limiting, redundancy | | Elevation of Privilege | Authorization | RBAC, least privilege |

STRIDE per Element Matrix

| DFD Element | S | T | R | I | D | E | | --------------- | --- | --- | --- | --- | --- | --- | | External Entity | X | | X | | | | | Process | X | X | X | X | X | X | | Data Store | | X | X | X | X | | | Data Flow | | X | | X | X | |

See: references/threat-modeling-guide.md

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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

| Use Case | Recommended Pattern | | ------------------ | ------------------------------------------ | | Web application | OAuth 2.0 + PKCE with OIDC | | API authentication | JWT with short expiration + refresh tokens | | Service-to-service | mTLS with certificate rotation | | CLI/Automation | API keys with IP allowlisting | | High security | FIDO2/WebAuthn hardware keys |

See: references/security-architecture-patterns.md

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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

| Impact \ Exploitability | Easy | Moderate | Difficult | | ----------------------- | -------- | -------- | --------- | | Critical | Critical | Critical | High | | High | Critical | High | Medium | | Medium | High | Medium | Low | | Low | Medium | Low | Low |

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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

| Category | Check | Risk | | ---------------- | ---------------------------------------------------- | ---------------------- | | Input Validation | All user input validated and sanitized | Injection | | Output Encoding | Context-appropriate encoding applied | XSS | | Authentication | Passwords hashed with Argon2/bcrypt | Credential theft | | Session | Secure cookie flags set (HttpOnly, Secure, SameSite) | Session hijacking | | Authorization | Server-side permission checks on all endpoints | Privilege escalation | | SQL | Parameterized queries used exclusively | SQL injection | | File Access | Path traversal sequences rejected | Path traversal | | Secrets | No hardcoded credentials or keys | Information disclosure | | Dependencies | Known vulnerable packages updated | Supply chain | | Logging | Sensitive data not logged | Information disclosure |

Secure vs Insecure Patterns

| Pattern | Issue | Secure Alternative | | ---------------------- | ------------------ | -------------------------------------------- | | SQL string formatting | SQL injection | Use parameterized queries with placeholders | | Shell command building | Command injection | Use subprocess with argument lists, no shell | | Path concatenation | Path traversal | Validate and canonicalize paths | | MD5/SHA1 for passwords | Weak hashing | Use Argon2id or bcrypt | | Math.random for tokens | Predictable values | Use crypto.getRandomValues |

Inline Code Examples

SQL Injection — insecure vs. secure (Python):

# ❌ Insecure: string formatting allows SQL injection
query = f"SELECT * FROM users WHERE username = '{username}'"
cursor.execute(query)

# ✅ Secure: parameterized query — user input never interpreted as SQL
query = "SELECT * FROM users WHERE username = %s"
cursor.execute(query, (username,))

Password Hashing with Argon2id (Python):

from argon2 import PasswordHasher

ph = PasswordHasher()          # uses secure defaults (time_cost, memory_cost)

# On registration
hashed = ph.hash(plain_password)

# On login — raises argon2.exceptions.VerifyMismatchError on failure
ph.verify(hashed, plain_password)

Secret Scanning — core pattern matching (Python):

import re, pathlib

SECRET_PATTERNS = {
    "aws_access_key":  re.compile(r"AKIA[0-9A-Z]{16}"),
    "github_token":    re.compile(r"ghp_[A-Za-z0-9]{36}"),
    "private_key":     re.compile(r"-----BEGIN (RSA |EC )?PRIVATE KEY-----"),
    "generic_secret":  re.compile(r'(?i)(password|secret|api_key)\s*=\s*["\']?\S{8,}'),
}

def scan_file(path: pathlib.Path) -> list[dict]:
    findings = []
    for lineno, line in enumerate(path.read_text(errors="replace").splitlines(), 1):
        for name, pattern in SECRET_PATTERNS.items():
            if pattern.search(line):
                findings.append({"file": str(path), "line": lineno, "type": name})
    return findings

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Incident Response Workflow

Respond to and contain security incidents.

Workflow: Handle Security Incident

1. Identify and triage:
   • Validate incident is genuine
   • Assess initial scope and severity
   • Activate incident response team
2. Contain the threat:
   • Isolate affected systems
   • Block malicious IPs/accounts
   • Disable compromised credentials
3. Eradicate root cause:
   • Remove malware/backdoors
   • Patch vulnerabilities
   • Update configurations
4. Recover operations:
   • Restore from clean backups
   • Verify system integrity
   • Monitor for recurrence
5. Conduct post-mortem:
   • Timeline reconstruction
   • Root cause analysis
   • Lessons learned
6. Implement improvements:
   • Update detection rules
   • Enhance controls
   • Update runbooks
7. Document and report
8. Validation: Threat contained; root cause eliminated; systems recovered; post-mortem complete; improvements implemented

Incident Severity Levels

| Level | Response Time | Escalation | | -------------------------------------------- | ------------- | -------------------------- | | P1 - Critical (active breach/exfiltration) | Immediate | CISO, Legal, Executive | | P2 - High (confirmed, contained) | 1 hour | Security Lead, IT Director | | P3 - Medium (potential, under investigation) | 4 hours | Security Team | | P4 - Low (suspicious, low impact) | 24 hours | On-call engineer |

Incident Response Checklist

| Phase | Actions | | --------------- | ------------------------------------------------------- | | Identification | Validate alert, assess scope, determine severity | | Containment | Isolate systems, preserve evidence, block access | | Eradication | Remove threat, patch vulnerabilities, reset credentials | | Recovery | Restore services, verify integrity, increase monitoring | | Lessons Learned | Document timeline, identify gaps, update procedures |

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Security Tools Reference

Recommended Security Tools

| Category | Tools | | ------------------- | --------------------------------------------------------- | | SAST | Semgrep, CodeQL, Bandit (Python), ESLint security plugins | | DAST | OWASP ZAP, Burp Suite, Nikto | | Dependency Scanning | Snyk, Dependabot, npm audit, pip-audit | | Secret Detection | GitLeaks, TruffleHog, detect-secrets | | Container Security | Trivy, Clair, Anchore | | Infrastructure | Checkov, tfsec, ScoutSuite | | Network | Wireshark, Nmap, Masscan | | Penetration | Metasploit, sqlmap, Burp Suite Pro |

Cryptographic Algorithm Selection

| Use Case | Algorithm | Key Size | | ---------------------- | ----------- | ------------------ | | Symmetric encryption | AES-256-GCM | 256 bits | | Password hashing | Argon2id | N/A (use defaults) | | Message authentication | HMAC-SHA256 | 256 bits | | Digital signatures | Ed25519 | 256 bits | | Key exchange | X25519 | 256 bits | | TLS | TLS 1.3 | N/A |

See: references/cryptography-implementation.md

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Tools and References

Scripts

| Script | Purpose | | ---------------------------------------------- | --------------------------------------------------------------------------------------------- | | threat_modeler.py | STRIDE threat analysis with DREAD risk scoring; JSON and text output; interactive guided mode | | secret_scanner.py | Detect hardcoded secrets and credentials across 20+ patterns; CI/CD integration ready |

For usage, see the inline code examples in Secure Code Review Workflow and the script source files directly.

References

| Document | Content | | --------------------------------------------------------------------------------- | ------------------------------------------------------------------- | | security-architecture-patterns.md | Zero Trust, defense-in-depth, authentication patterns, API security | | threat-modeling-guide.md | STRIDE methodology, attack trees, DREAD scoring, DFD creation | | cryptography-implementation.md | AES-GCM, RSA, Ed25519, password hashing, key management |

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Security Standards Reference

Security Headers Checklist

| Header | Recommended Value | | ------------------------- | ---------------------------------------- | | Content-Security-Policy | default-src self; script-src self | | X-Frame-Options | DENY | | X-Content-Type-Options | nosniff | | Strict-Transport-Security | max-age=31536000; includeSubDomains | | Referrer-Policy | strict-origin-when-cross-origin | | Permissions-Policy | geolocation=(), microphone=(), camera=() |

For compliance framework requirements (OWASP ASVS, CIS Benchmarks, NIST CSF, PCI-DSS, HIPAA, SOC 2), refer to the respective official documentation.

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Related Skills

| Skill | Integration Point | | ---------------------------------------- | ---------------------------------------- | | senior-devops | CI/CD security, infrastructure hardening | | senior-secops | Security monitoring, incident response | | senior-backend | Secure API development | | senior-architect | Security architecture decisions |

Creator: Engineering Team License: MIT Source Repo: neekware/ehaye-skills Source Bucket: engineering-team Original Path: engineering-team/senior-security