STRIDE Security Methodology

Guide for comprehensive security analysis using the STRIDE threat modeling framework, vulnerability assessment, and security architecture evaluation.

When to Use This Skill

Activate when:

• Conducting security threat modeling
• Performing vulnerability assessments
• Evaluating security architecture
• Creating security review documentation
• Generating threat model diagrams
• Assessing security posture of applications

STRIDE Framework

STRIDE categorizes security threats into six categories:

S - Spoofing

Identity theft/impersonation threats

• User authentication bypass
• Session hijacking
• Credential theft
• Certificate spoofing

T - Tampering

Data modification threats

• SQL injection
• Parameter manipulation
• Man-in-the-middle attacks
• Data store manipulation

R - Repudiation

Deniability threats

• Log tampering
• Missing audit trails
• Insufficient logging
• Non-repudiation failures

I - Information Disclosure

Data exposure threats

• Sensitive data leakage
• Error message exposure
• Directory traversal
• Improper access controls

D - Denial of Service

Availability threats

• Resource exhaustion
• Rate limiting bypass
• Memory leaks
• Infinite loops

E - Elevation of Privilege

Authorization bypass threats

• Privilege escalation
• Role bypass
• Insecure direct object reference
• Broken access control

Security Analysis Process

Phase 1: Asset Identification

1. Identify critical data assets
2. Map data flows and trust boundaries
3. Identify entry points and exit points
4. Document authentication mechanisms
5. List third-party dependencies

Phase 2: Threat Modeling

1. Apply STRIDE to each component
2. Identify threat scenarios
3. Assess likelihood and impact
4. Document attack vectors
5. Create threat diagrams

Phase 3: Vulnerability Assessment

1. Static code analysis
2. Dependency vulnerability scanning
3. Configuration review
4. Authentication/authorization testing
5. Input validation analysis

Phase 4: Risk Prioritization

1. Calculate risk scores
2. Prioritize by business impact
3. Identify quick wins
4. Create remediation roadmap
5. Document mitigations

Threat Model Template

## Threat: [STRIDE Category] - [Threat Name]

### Description
[Detailed threat description]

### Attack Vector
[How the attack could be executed]

### Affected Components
- [Component 1]
- [Component 2]

### Risk Assessment
- **Likelihood**: High/Medium/Low
- **Impact**: High/Medium/Low
- **Risk Score**: [Likelihood × Impact]

### Mitigation
- [Mitigation step 1]
- [Mitigation step 2]

### Verification
- [How to verify mitigation is effective]

Mermaid Diagram Patterns

Data Flow Diagram

graph LR
    A[User] -->|HTTPS| B[Load Balancer]
    B -->|Internal| C[App Server]
    C -->|Query| D[(Database)]
    C -->|API| E[External Service]

    style B fill:#f9f,stroke:#333
    style D fill:#bbf,stroke:#333

Trust Boundary Diagram

graph TB
    subgraph "Untrusted Zone"
        A[Internet Users]
    end

    subgraph "DMZ"
        B[Web Server]
    end

    subgraph "Trusted Zone"
        C[App Server]
        D[(Database)]
    end

    A --> B
    B --> C
    C --> D

Security Report Structure

# Security Assessment Report

## Executive Summary
- **Overall Risk Level**: [Critical/High/Medium/Low]
- **Critical Issues**: [Count]
- **High Issues**: [Count]
- **Recommendations**: [Top 3 actions]

## Threat Model Analysis
### STRIDE Coverage
- Spoofing: [Finding count]
- Tampering: [Finding count]
- Repudiation: [Finding count]
- Information Disclosure: [Finding count]
- Denial of Service: [Finding count]
- Elevation of Privilege: [Finding count]

## Architecture Diagram
[Mermaid diagram with trust boundaries]

## Findings

### Critical
1. [Finding with STRIDE category]

### High Priority
1. [Finding with STRIDE category]

## Remediation Roadmap
### Immediate (0-7 days)
- [Action items]

### Short-term (1-4 weeks)
- [Action items]

### Long-term (1-3 months)
- [Action items]

Key Principles

• Defense in Depth: Multiple security layers
• Least Privilege: Minimal access rights
• Secure by Default: Safe default configurations
• Fail Securely: Handle errors safely
• Zero Trust: Verify everything, trust nothing
• Data Classification: Protect based on sensitivity