MCP Time Server Node

# Security Assessment - MCP Time Server ## Current Security Measures ✅ ### 1. Input Validation - **Strong validation** for all parameters using dedicated validation functions - Type checking enforced by TypeScript - Timezone validation against date-fns-tz library - Date format validation with parseISO - Enum validation for time units and recurrence patterns - Numeric range validation (day of week, day of month) ### 2. Rate Limiting - Sliding window rate limiter implemented - Default: 100 requests per minute - Configurable via environment variables - Returns proper rate limit headers ### 3. Memory Protection - Cache has 10MB memory limit - Automatic eviction when limit reached - Memory-aware caching prevents DoS via cache flooding ### 4. No External Dependencies - No external API calls - No network requests - Reduces attack surface significantly ### 5. Error Handling - Structured error responses - No stack traces exposed to clients - Consistent error format ## Security Gaps & Recommendations 🚨 ### 1. Missing Security Linting **Risk**: Common security vulnerabilities may go undetected **Action Required**: Add ESLint security plugin ```bash npm install --save-dev eslint-plugin-security ``` Update `.eslintrc.json`: ```json { "plugins": ["@typescript-eslint", "security"], "extends": [ // ... existing "plugin:security/recommended" ] } ``` ### 2. Input Length Limits **Risk**: Large inputs could cause memory exhaustion or processing delays **Current State**: No explicit length limits on: - Timezone strings - Date strings - Format strings - Custom format patterns - Holiday arrays **Action Required**: Add length validation ```typescript // Add to validation.ts export const MAX_STRING_LENGTH = 1000; export const MAX_ARRAY_LENGTH = 365; // For holiday arrays export function validateStringLength(str: string, maxLength = MAX_STRING_LENGTH): boolean { return str.length <= maxLength; } ``` ### 3. JSON Injection Prevention **Risk**: While we use JSON.stringify safely, we should ensure no user input is parsed as JSON **Current State**: Good - we don't use JSON.parse on user input **Recommendation**: Document this as a security principle ### 4. Cache Key Injection **Risk**: Malicious cache keys could cause collisions or memory issues **Current State**: Cache keys include user input via JSON.stringify **Action Required**: Sanitize cache keys ```typescript // Use hash instead of raw user input import { createHash } from 'crypto'; function sanitizeCacheKey(key: string): string { return createHash('sha256').update(key).digest('hex').substring(0, 16); } ``` ### 5. Prototype Pollution **Risk**: Object spread/assign with user input **Current State**: Limited risk - we don't merge user objects **Recommendation**: Add tests to verify resistance ### 6. Regular Expression DoS (ReDoS) **Risk**: Complex regex patterns could cause CPU exhaustion **Current State**: We use simple regex patterns (low risk) **Action Required**: Document regex safety requirements ### 7. Missing Security Headers **Risk**: MCP protocol may not support security headers, but we should document this **Action Required**: Research MCP security best practices ## Testing Requirements (TDD) ### Security Test Suite Needed: 1. **Input validation extremes** - Very long strings (> 10KB) - Special characters in all fields - Unicode edge cases - Null bytes - Control characters 2. **Rate limiting effectiveness** - Burst attempts - Distributed attempts - Reset behavior 3. **Cache poisoning attempts** - Collision attempts - Memory exhaustion - Invalid data types 4. **Error disclosure** - Verify no sensitive info in errors - No file paths exposed - No internal state leaked ## MCP-Specific Security Considerations ### 1. Tool Parameter Injection **Risk**: MCP tools receive arbitrary JSON parameters **Mitigation**: - Never use parameters in shell commands - Never construct file paths from parameters - Never use eval() or Function() constructor ### 2. Resource Limits **Current**: Rate limiting only **Needed**: - Maximum execution time per tool call - Maximum memory usage per operation - Queue depth limits ### 3. Audit Logging **Current**: None **Recommendation**: Log security events - Rate limit violations - Invalid parameter attempts - Unusual patterns ## Security Tools to Add 1. **npm audit** - Already clean ✅ 2. **eslint-plugin-security** - Needed 3. **husky pre-commit** - Already configured ✅ 4. **OWASP Dependency Check** - Consider for CI/CD 5. **Snyk** - Consider for continuous monitoring ## Priority Actions 1. **HIGH**: Add input length validation 2. **HIGH**: Add eslint-plugin-security 3. **HIGH**: Write security test suite 4. **MEDIUM**: Implement cache key sanitization 5. **MEDIUM**: Add execution timeouts 6. **LOW**: Add security logging ## Summary The codebase has good foundational security: - Strong input validation - No external dependencies - Rate limiting - Memory limits However, it needs: - Security-focused linting - Input length limits - Security test coverage - Better documentation of security measures No critical vulnerabilities found, but implementing the recommendations above will significantly improve the security posture before any public release or CVE exposure.