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Input Validation

Input validation is a critical security feature in ZeroTrustKerberosLink that protects against a wide range of attacks including cross-site scripting (XSS), SQL injection, command injection, and path traversal.

Implementation Overview

ZeroTrustKerberosLink implements comprehensive input validation at multiple levels:

  1. Request Validation: All incoming HTTP requests are validated
  2. Parameter Validation: Individual parameters are validated based on expected type and format
  3. Content Validation: Request bodies are validated for structure and content
  4. Context-Aware Validation: Validation rules adapt based on the authentication context

Protection Against Common Attacks

XSS Protection

Cross-site scripting attacks are prevented through:

  • Output Encoding: All user-supplied data is properly encoded before rendering
  • Content Security Policy: Restricts execution of scripts to trusted sources
  • Input Sanitization: Removes potentially dangerous HTML and JavaScript
  • HTTP-only Cookies: Prevents JavaScript access to authentication cookies
# Example configuration for XSS protection
security:
  xss_protection:
    enabled: true
    sanitize_html: true
    content_security_policy: "default-src 'self'"

Injection Attack Prevention

Protection against SQL, NoSQL, LDAP, and command injection:

  • Parameterized Queries: All database queries use parameterization
  • Input Sanitization: Special characters are properly escaped
  • Allowlist Validation: Only permitted characters and patterns are allowed
  • Command Execution Controls: Strict controls on command execution
# Example configuration for injection protection
security:
  injection_protection:
    enabled: true
    sql_parameterization: true
    command_execution: false
    allowlist_patterns:
      - "^[a-zA-Z0-9_-]+$"

Path Traversal Protection

Prevention of directory traversal attacks:

  • Path Normalization: All file paths are normalized
  • Path Validation: Paths are validated against allowed directories
  • Symbolic Link Controls: Controls on symbolic link resolution
  • Access Controls: Strict file access controls
# Example configuration for path traversal protection
security:
  path_traversal_protection:
    enabled: true
    allowed_directories:
      - "/var/lib/zerotrustkerberos/data"
      - "/etc/zerotrustkerberos/config"
    allow_symlinks: false

Content Type Validation

Validation of request content types:

  • MIME Type Validation: Validates Content-Type headers
  • Content Structure Validation: Ensures request bodies match expected structure
  • Size Limits: Enforces size limits on request bodies
  • Character Encoding Validation: Validates character encoding
# Example configuration for content type validation
security:
  content_validation:
    enabled: true
    max_request_size: 1048576  # 1MB
    allowed_content_types:
      - "application/json"
      - "application/x-www-form-urlencoded"
    validate_utf8: true

Validation Framework

ZeroTrustKerberosLink uses a structured validation framework:

  1. Validation Rules: Defined rules for each input type
  2. Validation Chain: Multiple validation steps applied in sequence
  3. Validation Context: Context-aware validation based on authentication state
  4. Validation Reporting: Detailed reporting of validation failures

Configuration Options

The input validation system is highly configurable:

# Comprehensive input validation configuration
input_validation:
  enabled: true
  log_validation_failures: true
  strict_mode: true  # Reject requests that fail validation

  # XSS protection
  xss_protection:
    enabled: true
    sanitize_html: true

  # Injection protection
  injection_protection:
    enabled: true
    sql_parameterization: true

  # Path traversal protection
  path_traversal_protection:
    enabled: true
    allowed_directories:
      - "/var/lib/zerotrustkerberos/data"

  # Content validation
  content_validation:
    enabled: true
    max_request_size: 1048576  # 1MB
    allowed_content_types:
      - "application/json"

Best Practices

To maximize the effectiveness of input validation:

  1. Enable All Validation Features: Keep all validation features enabled
  2. Use Strict Mode: Reject requests that fail validation
  3. Log Validation Failures: Enable logging of validation failures
  4. Regular Updates: Keep validation rules updated
  5. Custom Rules: Add custom validation rules for your specific use case

Testing Input Validation

ZeroTrustKerberosLink includes tools to test input validation:

# Test input validation configuration
zerotrustkerberos-cli test validation

# Test specific validation rule
zerotrustkerberos-cli test validation --rule=xss

Input validation works in conjunction with other security features:

Further Reading