Broken Authentication

Category: Authentication & Authorization
Severity: Critical
MITRE ATT&CK Mapping: T1078 (Valid Accounts)

Description

Flawed authentication implementations allowing unauthorized access through weak, bypassed, or compromised authentication mechanisms in MCP systems.

Technical Details

Attack Vector

  • Weak authentication mechanisms
  • Authentication logic flaws
  • Credential validation failures
  • Authentication bypass vulnerabilities

Common Techniques

  • Weak password policies
  • Authentication timing attacks
  • Credential stuffing
  • Authentication logic bypasses

Impact

  • Account Takeover: Unauthorized access to user accounts
  • Identity Theft: Impersonation of legitimate users
  • System Compromise: Access to protected MCP resources
  • Privilege Escalation: Higher-level access through compromised authentication

Detection Methods

Authentication Monitoring

  • Monitor authentication attempts
  • Track authentication failures
  • Detect brute force attacks
  • Analyze authentication patterns

Credential Analysis

  • Monitor credential usage
  • Track password changes
  • Detect credential reuse
  • Analyze authentication methods

Mitigation Strategies

Authentication Strengthening

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

Security Controls

  • Implement rate limiting
  • Use account lockout policies
  • Deploy authentication logging
  • Monitor authentication patterns

Real-World Examples

Example 1: Weak Password Validation

def authenticate_user(username, password):
    user = get_user(username)
    
    # Weak password validation
    if user and user.password == password:
        return True
    return False
    
    # Should use: secure_password_hash_compare()

Example 2: Authentication Timing Attack

def validate_credentials(username, password):
    users = get_all_users()
    
    # Timing attack vulnerability
    for user in users:
        if user.username == username:
            if user.password == password:
                return True
            return False
    return False
    
    # Should use: constant_time_compare()

Example 3: Authentication Logic Bypass

def login(username, password, remember_me=False):
    # Authentication bypass through parameter
    if remember_me and username in remembered_users:
        return create_session(username)
    
    # Normal authentication
    if authenticate_user(username, password):
        return create_session(username)
    
    return None

References & Sources

  • Philippe Bogaerts - “The Security Risks of Model Context Protocol (MCP)”
  • Red Hat - “Model Context Protocol (MCP): Understanding security risks and controls”

Broken authentication represents a critical vulnerability that undermines the entire security foundation of MCP systems.