Unauthenticated Access

Category: Authentication & Authorization
Severity: Critical
MITRE ATT&CK Mapping: T1190 (Exploit Public-Facing Application)

Description

MCP endpoints exposed without proper authentication mechanisms, allowing attackers to access protected resources and functionality without providing valid credentials.

Technical Details

Attack Vector

  • Exposed MCP endpoints without authentication
  • Missing authentication checks
  • Bypassed authentication requirements
  • Open access to protected resources

Common Techniques

  • Direct endpoint access
  • Authentication bypass
  • Missing authentication validation
  • Default open access

Impact

  • Unauthorized Access: Access to protected MCP resources
  • Data Exposure: Sensitive information accessible without authentication
  • System Compromise: Control over MCP functionality
  • Service Abuse: Misuse of MCP services without authorization

Detection Methods

Access Monitoring

  • Monitor endpoint access patterns
  • Track unauthenticated requests
  • Detect unauthorized access attempts
  • Analyze access logs

Authentication Analysis

  • Monitor authentication failures
  • Track missing authentication
  • Detect authentication bypass attempts
  • Analyze authentication patterns

Mitigation Strategies

Authentication Implementation

  • Implement strong authentication
  • Use multi-factor authentication
  • Deploy authentication validation
  • Monitor authentication events

Access Controls

  • Implement authorization checks
  • Use role-based access control
  • Deploy access validation
  • Monitor access attempts

Real-World Examples

Example 1: Open MCP Endpoint

@app.route('/mcp/tools', methods=['GET'])
def get_tools():
    # No authentication check
    return jsonify(get_all_tools())
    
    # Should include: require_authentication()

Example 2: Missing Authentication Validation

def execute_tool(tool_name, parameters):
    # No authentication validation
    tool = get_tool(tool_name)
    return tool.execute(parameters)
    
    # Should include: validate_user_authentication()

Example 3: Bypassed Authentication

def admin_action(action):
    # Authentication bypass through parameter
    if action == "emergency_access":
        return perform_admin_action()
    
    # Normal authentication only for non-emergency
    if not authenticate_user():
        return "Unauthorized"
    
    return perform_admin_action()

References & Sources

  • AppSecEngineer - “5 Critical MCP Vulnerabilities Every Security Team Should Know”
  • Equixly - “MCP Servers: The New Security Nightmare”
  • Red Hat - “Model Context Protocol (MCP): Understanding security risks and controls”

Unauthenticated access represents a fundamental security failure that can lead to complete system compromise.