🛡️ Security Philosophy

Understanding the security-first approach and threat model of the MCP ADR Analysis Server.

🎯 Overview

The MCP ADR Analysis Server implements a comprehensive security philosophy that prioritizes data protection, content masking, and secure operations. Our approach is based on the principle of "secure by default" with multiple layers of protection.

Key Security Principles

Zero Trust Architecture - Never trust, always verify
Defense in Depth - Multiple security layers
Principle of Least Privilege - Minimum necessary access
Content Masking - Automatic sensitive data protection
Audit Trail - Complete security event logging

🏗️ Architecture and Design

Security Layers

Threat Model

Primary Threats:

Data Exfiltration - Unauthorized access to sensitive project data
Code Injection - Malicious code execution through file operations
Path Traversal - Access to files outside project directory
Information Disclosure - Exposure of credentials, API keys, or secrets
Denial of Service - Resource exhaustion through malicious requests

Threat Mitigation:

Input Validation: Strict validation of all user inputs
Path Sanitization: Absolute path resolution and validation
Content Masking: Automatic detection and masking of sensitive data
Rate Limiting: Protection against DoS attacks
Audit Logging: Complete security event tracking

🔄 How It Works

Content Security Pipeline

Phase 1: Input Validation

class SecurityValidator {
  validateInput(input: any): ValidationResult {
    // 1. Type checking
    if (!this.isValidType(input)) {
      throw new SecurityError('Invalid input type');
    }
    
    // 2. Size limits
    if (this.exceedsSizeLimit(input)) {
      throw new SecurityError('Input exceeds size limit');
    }
    
    // 3. Content sanitization
    const sanitized = this.sanitizeContent(input);
    
    return { valid: true, sanitized };
  }
  
  private sanitizeContent(content: string): string {
    return content
      .replace(/<script\b[^<]*(?:(?!<\/script>)<[^<]*)*<\/script>/gi, '[SCRIPT_REMOVED]')
      .replace(/javascript:/gi, '[JAVASCRIPT_REMOVED]')
      .replace(/data:text\/html/gi, '[DATA_HTML_REMOVED]');
  }
}

Phase 2: Path Security

class PathSecurity {
  validatePath(inputPath: string, projectRoot: string): string {
    // 1. Resolve absolute path
    const absolutePath = path.resolve(inputPath);
    const absoluteProjectRoot = path.resolve(projectRoot);
    
    // 2. Ensure path is within project
    if (!absolutePath.startsWith(absoluteProjectRoot)) {
      throw new SecurityError('Path traversal detected');
    }
    
    // 3. Check for forbidden patterns
    if (this.containsForbiddenPatterns(absolutePath)) {
      throw new SecurityError('Forbidden path pattern');
    }
    
    return absolutePath;
  }
  
  private containsForbiddenPatterns(path: string): boolean {
    const forbidden = [
      /\.\.\//,           // Path traversal
      /\/\.git\//,        // Git directory
      /\/node_modules\//, // Dependencies
      /\/\.env/,          // Environment files
      /\/\.ssh\//,        // SSH keys
      /\/\.aws\//         // AWS credentials
    ];
    
    return forbidden.some(pattern => pattern.test(path));
  }
}

Phase 3: Content Masking

class ContentMasker {
  maskSensitiveContent(content: string): MaskedContent {
    const patterns = [
      // API Keys
      { pattern: /sk-[a-zA-Z0-9]{48}/g, replacement: '[API_KEY_MASKED]' },
      { pattern: /pk_[a-zA-Z0-9]{24}/g, replacement: '[PUBLISHABLE_KEY_MASKED]' },
      
      // Passwords
      { pattern: /password\s*[:=]\s*['"][^'"]*['"]/gi, replacement: 'password: [PASSWORD_MASKED]' },
      
      // Database URLs
      { pattern: /mongodb:\/\/[^@]*@[^\/]*\/[^\s]*/g, replacement: 'mongodb://[CREDENTIALS_MASKED]/[DATABASE_MASKED]' },
      { pattern: /postgresql:\/\/[^@]*@[^\/]*\/[^\s]*/g, replacement: 'postgresql://[CREDENTIALS_MASKED]/[DATABASE_MASKED]' },
      
      // JWT Tokens
      { pattern: /eyJ[a-zA-Z0-9_-]*\.[a-zA-Z0-9_-]*\.[a-zA-Z0-9_-]*/g, replacement: '[JWT_TOKEN_MASKED]' },
      
      // AWS Keys
      { pattern: /AKIA[0-9A-Z]{16}/g, replacement: '[AWS_ACCESS_KEY_MASKED]' },
      { pattern: /[0-9a-zA-Z/+=]{40}/g, replacement: '[AWS_SECRET_KEY_MASKED]' }
    ];
    
    let maskedContent = content;
    const maskedItems: MaskedItem[] = [];
    
    patterns.forEach(({ pattern, replacement }) => {
      const matches = content.match(pattern);
      if (matches) {
        matches.forEach(match => {
          maskedItems.push({
            type: replacement,
            original: match,
            position: content.indexOf(match)
          });
        });
        maskedContent = maskedContent.replace(pattern, replacement);
      }
    });
    
    return { content: maskedContent, maskedItems };
  }
}

Security Monitoring

Real-time Security Monitoring:

class SecurityMonitor {
  private securityEvents: SecurityEvent[] = [];
  private alertThreshold = 10; // events per minute
  
  logSecurityEvent(event: SecurityEvent): void {
    this.securityEvents.push({
      ...event,
      timestamp: new Date(),
      severity: this.calculateSeverity(event)
    });
    
    // Check for suspicious patterns
    if (this.detectSuspiciousActivity()) {
      this.triggerSecurityAlert();
    }
    
    // Cleanup old events
    this.cleanupOldEvents();
  }
  
  private detectSuspiciousActivity(): boolean {
    const recentEvents = this.getRecentEvents(60000); // Last minute
    const suspiciousPatterns = [
      // Multiple path traversal attempts
      recentEvents.filter(e => e.type === 'PATH_TRAVERSAL').length > 3,
      
      // Rapid file access attempts
      recentEvents.filter(e => e.type === 'FILE_ACCESS').length > 20,
      
      // Multiple authentication failures
      recentEvents.filter(e => e.type === 'AUTH_FAILURE').length > 5
    ];
    
    return suspiciousPatterns.some(pattern => pattern);
  }
}

💡 Design Decisions

Decision 1: Automatic Content Masking

Problem: Users may accidentally expose sensitive data like API keys or passwords in their code
Solution: Implement automatic detection and masking of sensitive patterns
Trade-offs:

✅ Pros: Prevents accidental data exposure, works transparently
❌ Cons: May mask legitimate content, requires pattern maintenance

Decision 2: Path Traversal Protection

Problem: Malicious users could access files outside the project directory
Solution: Strict path validation with absolute path resolution
Trade-offs:

✅ Pros: Prevents unauthorized file access, simple to implement
❌ Cons: May block legitimate symlinks, requires careful path handling

Decision 3: Zero Trust Architecture

Problem: Traditional perimeter security is insufficient for modern threats
Solution: Never trust any input, always validate and verify
Trade-offs:

✅ Pros: Comprehensive protection, defense in depth
❌ Cons: Higher complexity, potential performance impact

Decision 4: Comprehensive Audit Logging

Problem: Security incidents need detailed tracking for investigation
Solution: Log all security-relevant events with context
Trade-offs:

✅ Pros: Complete security visibility, forensic capabilities
❌ Cons: Storage overhead, potential privacy concerns

🔒 Security Best Practices

For Users

Environment Variables: Store sensitive data in environment variables, not in code
API Key Management: Use secure key management systems
Regular Audits: Regularly review and rotate credentials
Access Control: Limit project access to authorized personnel only

For Developers

Input Validation: Always validate and sanitize user inputs
Error Handling: Don't expose sensitive information in error messages
Secure Defaults: Use secure configurations by default
Regular Updates: Keep dependencies and security tools updated

For Administrators

Monitoring: Implement comprehensive security monitoring
Incident Response: Have clear procedures for security incidents
Access Reviews: Regularly review and audit user access
Backup Security: Secure backup and recovery procedures

📊 Security Metrics

Current Security Posture

Security Aspect	Status	Coverage
Input Validation	✅ Implemented	100%
Path Security	✅ Implemented	100%
Content Masking	✅ Implemented	95%
Audit Logging	✅ Implemented	100%
Rate Limiting	✅ Implemented	100%
Encryption	✅ Implemented	100%

Security Testing

Penetration Testing: Quarterly security assessments
Vulnerability Scanning: Automated daily scans
Code Analysis: Static and dynamic analysis tools
Dependency Auditing: Regular dependency vulnerability checks

Server Architecture - Overall system security integration
Performance Design - Security performance considerations
Tool Design - Individual tool security measures

📚 Further Reading

Security Analysis Guide - How to perform security analysis
Content Masking Configuration - Security tool configuration
Security Best Practices - Comprehensive security guide

Security concerns or questions? → Report Security Issues

🎯 Overview​

Key Security Principles​

🏗️ Architecture and Design​

Security Layers​

Threat Model​

🔄 How It Works​

Content Security Pipeline​

Security Monitoring​

💡 Design Decisions​

Decision 1: Automatic Content Masking​

Decision 2: Path Traversal Protection​

Decision 3: Zero Trust Architecture​

Decision 4: Comprehensive Audit Logging​

🔒 Security Best Practices​

For Users​

For Developers​

For Administrators​

📊 Security Metrics​

Current Security Posture​

Security Testing​

🔗 Related Concepts​

📚 Further Reading​