ZeroTrustKerberosLink Security Features Technical Documentation¶

Overview¶

ZeroTrustKerberosLink implements comprehensive security features as part of its security-first design philosophy. This document provides detailed technical information about the security features implemented in ZeroTrustKerberosLink, with a focus on input validation, security headers, secure communication, and other security hardening measures.

Input Validation¶

ZeroTrustKerberosLink implements robust input validation to protect against injection attacks, cross-site scripting (XSS), and other input-based vulnerabilities.

Validation Framework¶

Our input validation framework follows these principles:

Validate All Inputs: Every input from untrusted sources is validated
Positive Security Model: Only allow known good input patterns
Defense in Depth: Multiple validation layers for critical inputs
Contextual Validation: Input validation appropriate to the context

Implementation Details¶

HTTP Parameter Validation¶

def validate_http_parameter(param_name, param_value, validation_rules):
    """
    Validates HTTP parameters against defined rules.

    Args:
        param_name: Name of the parameter
        param_value: Value to validate
        validation_rules: Dictionary of validation rules

    Returns:
        (bool, str): Validation result and error message if any
    """
    # Type validation
    if validation_rules.get('type') == 'string' and not isinstance(param_value, str):
        return False, f"Parameter {param_name} must be a string"

    # Length validation
    if 'min_length' in validation_rules and len(param_value) < validation_rules['min_length']:
        return False, f"Parameter {param_name} must be at least {validation_rules['min_length']} characters"

    if 'max_length' in validation_rules and len(param_value) > validation_rules['max_length']:
        return False, f"Parameter {param_name} must be at most {validation_rules['max_length']} characters"

    # Pattern validation
    if 'pattern' in validation_rules and not re.match(validation_rules['pattern'], param_value):
        return False, f"Parameter {param_name} does not match required pattern"

    # Enumeration validation
    if 'enum' in validation_rules and param_value not in validation_rules['enum']:
        return False, f"Parameter {param_name} must be one of: {', '.join(validation_rules['enum'])}"

    return True, ""

JSON Payload Validation¶

JSON payloads are validated using a schema-based approach:

def validate_json_payload(payload, schema):
    """
    Validates JSON payload against a defined schema.

    Args:
        payload: JSON payload to validate
        schema: JSON schema for validation

    Returns:
        (bool, str): Validation result and error message if any
    """
    try:
        jsonschema.validate(instance=payload, schema=schema)
        return True, ""
    except jsonschema.exceptions.ValidationError as e:
        return False, f"JSON validation error: {str(e)}"

Path Traversal Protection¶

def validate_file_path(path):
    """
    Validates file paths to prevent path traversal attacks.

    Args:
        path: File path to validate

    Returns:
        (bool, str): Validation result and error message if any
    """
    # Normalize path
    normalized_path = os.path.normpath(path)

    # Check for path traversal attempts
    if '..' in normalized_path or normalized_path.startswith('/'):
        return False, "Invalid file path"

    # Check if path is within allowed directory
    allowed_dir = config.get('allowed_directory')
    absolute_path = os.path.abspath(os.path.join(allowed_dir, normalized_path))
    if not absolute_path.startswith(allowed_dir):
        return False, "Path outside of allowed directory"

    return True, ""

Content Type Validation¶

All requests with bodies are validated for correct Content-Type:

def validate_content_type(request, expected_type):
    """
    Validates the Content-Type header of a request.

    Args:
        request: HTTP request object
        expected_type: Expected Content-Type

    Returns:
        (bool, str): Validation result and error message if any
    """
    content_type = request.headers.get('Content-Type', '')

    if not content_type.startswith(expected_type):
        return False, f"Invalid Content-Type. Expected {expected_type}"

    return True, ""

Security Headers¶

ZeroTrustKerberosLink implements comprehensive security headers to protect against common web vulnerabilities.

Content Security Policy (CSP)¶

Our CSP implementation follows the principle of least privilege:

def apply_content_security_policy(response):
    """
    Applies Content Security Policy header to HTTP response.

    Args:
        response: HTTP response object

    Returns:
        HTTP response with CSP header
    """
    csp_directives = [
        "default-src 'self'",
        "script-src 'self' https://cdnjs.cloudflare.com",
        "style-src 'self' https://cdnjs.cloudflare.com https://fonts.googleapis.com",
        "font-src 'self' https://cdnjs.cloudflare.com https://fonts.gstatic.com",
        "img-src 'self' data:",
        "connect-src 'self'",
        "frame-ancestors 'none'",
        "form-action 'self'",
        "base-uri 'self'",
        "object-src 'none'"
    ]

    response.headers['Content-Security-Policy'] = '; '.join(csp_directives)
    return response

HTTP Strict Transport Security (HSTS)¶

HSTS is implemented to ensure secure connections:

def apply_hsts(response):
    """
    Applies HTTP Strict Transport Security header.

    Args:
        response: HTTP response object

    Returns:
        HTTP response with HSTS header
    """
    response.headers['Strict-Transport-Security'] = 'max-age=31536000; includeSubDomains; preload'
    return response

X-Content-Type-Options¶

Protection against MIME type confusion attacks:

def apply_content_type_options(response):
    """
    Applies X-Content-Type-Options header.

    Args:
        response: HTTP response object

    Returns:
        HTTP response with X-Content-Type-Options header
    """
    response.headers['X-Content-Type-Options'] = 'nosniff'
    return response

X-Frame-Options¶

Protection against clickjacking:

def apply_frame_options(response):
    """
    Applies X-Frame-Options header.

    Args:
        response: HTTP response object

    Returns:
        HTTP response with X-Frame-Options header
    """
    response.headers['X-Frame-Options'] = 'DENY'
    return response

X-XSS-Protection¶

Additional layer of XSS protection:

def apply_xss_protection(response):
    """
    Applies X-XSS-Protection header.

    Args:
        response: HTTP response object

    Returns:
        HTTP response with X-XSS-Protection header
    """
    response.headers['X-XSS-Protection'] = '1; mode=block'
    return response

Referrer Policy¶

Control over referrer information:

def apply_referrer_policy(response):
    """
    Applies Referrer-Policy header.

    Args:
        response: HTTP response object

    Returns:
        HTTP response with Referrer-Policy header
    """
    response.headers['Referrer-Policy'] = 'strict-origin-when-cross-origin'
    return response

Permissions Policy¶

Restrict browser features:

def apply_permissions_policy(response):
    """
    Applies Permissions-Policy header.

    Args:
        response: HTTP response object

    Returns:
        HTTP response with Permissions-Policy header
    """
    permissions = [
        "camera=()",
        "microphone=()",
        "geolocation=()"
    ]

    response.headers['Permissions-Policy'] = ', '.join(permissions)
    return response

Cache Control¶

Prevent caching of sensitive information:

def apply_cache_control(response, is_sensitive=False):
    """
    Applies appropriate Cache-Control headers.

    Args:
        response: HTTP response object
        is_sensitive: Whether the response contains sensitive information

    Returns:
        HTTP response with Cache-Control header
    """
    if is_sensitive:
        response.headers['Cache-Control'] = 'no-store, max-age=0'
    else:
        response.headers['Cache-Control'] = 'public, max-age=3600'

    return response

Secure Redis Communication¶

ZeroTrustKerberosLink implements secure Redis communication for caching and session management.

TLS Support¶

def create_secure_redis_connection(config):
    """
    Creates a secure Redis connection with TLS.

    Args:
        config: Redis configuration

    Returns:
        Redis connection object
    """
    return redis.Redis(
        host=config['host'],
        port=config['port'],
        password=config['password'],
        ssl=True,
        ssl_ca_certs=config['ca_cert_path'],
        ssl_cert_reqs='required'
    )

Secure Credential Handling¶

def get_redis_credentials():
    """
    Securely retrieves Redis credentials.

    Returns:
        Dictionary with Redis credentials
    """
    # Retrieve from secure credential store
    credential_store = SecureCredentialStore()

    return {
        'host': credential_store.get('REDIS_HOST'),
        'port': credential_store.get('REDIS_PORT'),
        'password': credential_store.get('REDIS_PASSWORD'),
        'ca_cert_path': credential_store.get('REDIS_CA_CERT_PATH')
    }

Connection Pooling with Timeouts¶

def create_redis_connection_pool(config):
    """
    Creates a Redis connection pool with appropriate timeouts.

    Args:
        config: Redis configuration

    Returns:
        Redis connection pool
    """
    return redis.ConnectionPool(
        host=config['host'],
        port=config['port'],
        password=config['password'],
        ssl=True,
        ssl_ca_certs=config['ca_cert_path'],
        socket_timeout=5.0,
        socket_connect_timeout=2.0,
        max_connections=10
    )

Error Handling and Logging¶

def redis_operation_with_error_handling(operation_func):
    """
    Decorator for Redis operations with error handling.

    Args:
        operation_func: Redis operation function

    Returns:
        Wrapped function with error handling
    """
    @functools.wraps(operation_func)
    def wrapper(*args, **kwargs):
        try:
            return operation_func(*args, **kwargs)
        except redis.ConnectionError as e:
            logger.error(f"Redis connection error: {str(e)}")
            # Implement fallback mechanism
            return None
        except redis.RedisError as e:
            logger.error(f"Redis error: {str(e)}")
            # Implement fallback mechanism
            return None

    return wrapper

Secure Cache Operations¶

@redis_operation_with_error_handling
def cache_set(key, value, expiration=3600):
    """
    Securely sets a cache value with expiration.

    Args:
        key: Cache key
        value: Value to cache
        expiration: Expiration time in seconds

    Returns:
        Boolean indicating success
    """
    # Prefix key with namespace
    prefixed_key = f"{config.get('cache_namespace')}:{key}"

    # Serialize value
    serialized_value = json.dumps(value)

    # Set with expiration
    return redis_client.setex(prefixed_key, expiration, serialized_value)

@redis_operation_with_error_handling
def cache_get(key):
    """
    Securely retrieves a cached value.

    Args:
        key: Cache key

    Returns:
        Cached value or None
    """
    # Prefix key with namespace
    prefixed_key = f"{config.get('cache_namespace')}:{key}"

    # Get value
    value = redis_client.get(prefixed_key)

    # Deserialize if not None
    if value is not None:
        return json.loads(value)

    return None

Rate Limiting¶

ZeroTrustKerberosLink implements rate limiting to protect against abuse and denial of service attacks.

Rate Limit Configuration¶

RATE_LIMIT_CONFIG = {
    'default': {
        'limit': 100,
        'period': 60  # seconds
    },
    'authentication': {
        'limit': 5,
        'period': 60
    },
    'api': {
        'limit': 60,
        'period': 60
    }
}

Rate Limit Implementation¶

def rate_limit(request, limit_type='default'):
    """
    Implements rate limiting for requests.

    Args:
        request: HTTP request object
        limit_type: Type of rate limit to apply

    Returns:
        (bool, int): Whether request is allowed and remaining limit
    """
    # Get client identifier (IP address or user ID)
    client_id = get_client_identifier(request)

    # Get rate limit configuration
    config = RATE_LIMIT_CONFIG.get(limit_type, RATE_LIMIT_CONFIG['default'])
    limit = config['limit']
    period = config['period']

    # Create rate limit key
    rate_limit_key = f"rate_limit:{limit_type}:{client_id}"

    # Get current count
    count = int(redis_client.get(rate_limit_key) or 0)

    # Check if limit exceeded
    if count >= limit:
        return False, 0

    # Increment count
    pipe = redis_client.pipeline()
    pipe.incr(rate_limit_key)
    pipe.expire(rate_limit_key, period)
    pipe.execute()

    # Return result
    return True, limit - count - 1

Rate Limit Headers¶

def apply_rate_limit_headers(response, remaining, limit, reset_time):
    """
    Applies rate limit headers to response.

    Args:
        response: HTTP response object
        remaining: Remaining requests
        limit: Rate limit
        reset_time: Time when rate limit resets

    Returns:
        HTTP response with rate limit headers
    """
    response.headers['X-RateLimit-Limit'] = str(limit)
    response.headers['X-RateLimit-Remaining'] = str(remaining)
    response.headers['X-RateLimit-Reset'] = str(reset_time)

    return response

Authentication Security¶

ZeroTrustKerberosLink implements secure authentication mechanisms.

Kerberos Authentication¶

def authenticate_kerberos(request):
    """
    Authenticates a request using Kerberos.

    Args:
        request: HTTP request object

    Returns:
        (bool, dict): Authentication result and user information
    """
    # Get Kerberos ticket from request
    ticket = request.headers.get('Authorization', '').replace('Negotiate ', '')

    if not ticket:
        return False, {'error': 'No Kerberos ticket provided'}

    try:
        # Validate Kerberos ticket
        auth_context = gssapi.SecurityContext(usage="accept")
        auth_context.step(base64.b64decode(ticket))

        if not auth_context.complete:
            return False, {'error': 'Incomplete Kerberos authentication'}

        # Get authenticated user
        user = auth_context.initiator_name

        return True, {'user': str(user)}
    except gssapi.exceptions.GSSError as e:
        logger.error(f"Kerberos authentication error: {str(e)}")
        return False, {'error': 'Kerberos authentication failed'}

Multi-Factor Authentication¶

def require_mfa(user_id, mfa_type='totp'):
    """
    Determines if MFA is required for a user.

    Args:
        user_id: User identifier
        mfa_type: Type of MFA

    Returns:
        bool: Whether MFA is required
    """
    # Get user MFA configuration
    user_config = get_user_config(user_id)

    # Check if MFA is enabled
    if not user_config.get('mfa_enabled', False):
        return False

    # Check if MFA is required for this session
    risk_score = calculate_session_risk(user_id)
    if risk_score < user_config.get('mfa_risk_threshold', 50):
        return False

    return True

def verify_mfa(user_id, mfa_code, mfa_type='totp'):
    """
    Verifies MFA code.

    Args:
        user_id: User identifier
        mfa_code: MFA code provided by user
        mfa_type: Type of MFA

    Returns:
        bool: Whether MFA code is valid
    """
    if mfa_type == 'totp':
        # Get user's TOTP secret
        totp_secret = get_user_totp_secret(user_id)

        # Verify TOTP code
        totp = pyotp.TOTP(totp_secret)
        return totp.verify(mfa_code)
    elif mfa_type == 'push':
        # Check push notification status
        return check_push_notification_status(user_id, mfa_code)
    else:
        return False

Secure AWS Integration¶

ZeroTrustKerberosLink securely integrates with AWS services.

Temporary Credential Generation¶

def generate_aws_credentials(user_id, aws_role_arn):
    """
    Generates temporary AWS credentials.

    Args:
        user_id: User identifier
        aws_role_arn: AWS role ARN

    Returns:
        dict: Temporary AWS credentials
    """
    # Create STS client
    sts_client = boto3.client('sts')

    # Generate session name
    session_name = f"ZeroTrustKerberosLink-{user_id}-{int(time.time())}"

    try:
        # Assume role with STS
        response = sts_client.assume_role(
            RoleArn=aws_role_arn,
            RoleSessionName=session_name,
            DurationSeconds=3600  # 1 hour
        )

        # Extract credentials
        credentials = response['Credentials']

        return {
            'AccessKeyId': credentials['AccessKeyId'],
            'SecretAccessKey': credentials['SecretAccessKey'],
            'SessionToken': credentials['SessionToken'],
            'Expiration': credentials['Expiration'].isoformat()
        }
    except botocore.exceptions.ClientError as e:
        logger.error(f"AWS credential generation error: {str(e)}")
        raise

Secure Role Mapping¶

def map_user_to_aws_role(user_id, user_groups):
    """
    Maps a user to appropriate AWS IAM role.

    Args:
        user_id: User identifier
        user_groups: List of user's groups

    Returns:
        str: AWS role ARN
    """
    # Get role mapping configuration
    role_mapping = get_role_mapping_config()

    # Check for direct user mapping
    if user_id in role_mapping.get('users', {}):
        return role_mapping['users'][user_id]

    # Check for group mapping
    for group in user_groups:
        if group in role_mapping.get('groups', {}):
            return role_mapping['groups'][group]

    # Return default role if no mapping found
    return role_mapping.get('default')

Audit Logging¶

ZeroTrustKerberosLink implements comprehensive audit logging for security events.

Log Format¶

def create_audit_log(event_type, user_id, success, details=None):
    """
    Creates an audit log entry.

    Args:
        event_type: Type of event
        user_id: User identifier
        success: Whether the event was successful
        details: Additional event details

    Returns:
        dict: Audit log entry
    """
    log_entry = {
        'timestamp': datetime.datetime.utcnow().isoformat(),
        'event_type': event_type,
        'user_id': user_id,
        'success': success,
        'source_ip': get_client_ip(),
        'user_agent': get_user_agent(),
        'request_id': get_request_id()
    }

    if details:
        log_entry['details'] = details

    return log_entry

Log Storage¶

def store_audit_log(log_entry):
    """
    Stores an audit log entry.

    Args:
        log_entry: Audit log entry

    Returns:
        bool: Whether storage was successful
    """
    # Determine storage backend
    storage_backend = config.get('audit_log_storage', 'file')

    if storage_backend == 'file':
        return store_audit_log_file(log_entry)
    elif storage_backend == 'database':
        return store_audit_log_database(log_entry)
    elif storage_backend == 'cloudwatch':
        return store_audit_log_cloudwatch(log_entry)
    else:
        logger.error(f"Unknown audit log storage backend: {storage_backend}")
        return False

Log Integrity¶

def ensure_log_integrity(log_entry):
    """
    Ensures integrity of audit log entry.

    Args:
        log_entry: Audit log entry

    Returns:
        dict: Audit log entry with integrity information
    """
    # Create log entry JSON
    log_json = json.dumps(log_entry, sort_keys=True)

    # Calculate hash
    log_hash = hashlib.sha256(log_json.encode()).hexdigest()

    # Add hash to log entry
    log_entry['integrity_hash'] = log_hash

    return log_entry

Conclusion¶

ZeroTrustKerberosLink implements comprehensive security features as part of its security hardening efforts. These features protect against common vulnerabilities and provide a secure foundation for integrating Kerberos authentication with AWS services. By implementing robust input validation, security headers, secure Redis communication, and other security measures, ZeroTrustKerberosLink ensures that organizations can maintain a strong security posture while leveraging the benefits of AWS integration.