Resource Access Control Bypass

Category: Privilege & Access Control
Severity: High
MITRE ATT&CK Mapping: T1070 (Indicator Removal on Host)

Description

Circumventing access control mechanisms to gain unauthorized access to protected resources, files, databases, and system components within MCP environments.

Technical Details

Attack Vector

  • Access control implementation flaws
  • Permission bypass techniques
  • Resource protection weaknesses
  • Authorization mechanism failures

Common Techniques

  • Permission system bypass
  • Access control circumvention
  • Resource enumeration
  • Authorization token manipulation

Impact

  • Unauthorized Access: Access to protected resources and data
  • Data Exposure: Exposure of sensitive information
  • System Compromise: Access to critical system components
  • Privacy Violation: Unauthorized access to user data

Detection Methods

Access Monitoring

  • Monitor resource access patterns
  • Track authorization attempts
  • Detect access control violations
  • Analyze permission usage

Resource Monitoring

  • Monitor resource usage
  • Track unauthorized access
  • Detect permission bypass
  • Analyze resource protection

Mitigation Strategies

Access Control

  • Implement robust access controls
  • Use authorization frameworks
  • Deploy access monitoring
  • Regular access audits

Resource Protection

  • Implement resource protection
  • Use encryption for sensitive data
  • Deploy access logging
  • Monitor resource usage

Real-World Examples

Example 1: File Access Control Bypass

# Vulnerable file access control
class FileAccessControl:
    def __init__(self):
        self.permissions = {
            "user1": ["read"],
            "user2": ["read", "write"],
            "admin": ["read", "write", "delete"]
        }
    
    def check_access(self, user, file_path, action):
        # Flawed access control logic
        if user in self.permissions:
            if action in self.permissions[user]:
                return True
        
        # Bypass: using relative paths
        if "../" in file_path:
            return True  # Should be False
        
        # Attacker bypasses access control
        # file_path = "../../../etc/passwd"

Example 2: Database Access Control Bypass

# Vulnerable database access control
class DatabaseAccessControl:
    def __init__(self):
        self.user_permissions = {
            "read_user": ["SELECT"],
            "write_user": ["SELECT", "INSERT", "UPDATE"],
            "admin": ["SELECT", "INSERT", "UPDATE", "DELETE"]
        }
    
    def execute_query(self, user, query):
        # Insufficient query validation
        if user in self.user_permissions:
            # Should validate query against permissions
            return self.db.execute(query)
        
        # Attacker injects privileged operations
        # query = "SELECT * FROM users; DROP TABLE users;"

Example 3: API Access Control Bypass

# Vulnerable API access control
class APIAccessControl:
    def __init__(self):
        self.protected_endpoints = [
            "/admin/users",
            "/admin/settings",
            "/admin/logs"
        ]
    
    def check_endpoint_access(self, user, endpoint):
        # Flawed endpoint protection
        if endpoint in self.protected_endpoints:
            if user.role == "admin":
                return True
            return False
        
        # Bypass: case sensitivity flaw
        if endpoint.lower() in [ep.lower() for ep in self.protected_endpoints]:
            return False
        
        # Attacker bypasses with case variation
        # endpoint = "/Admin/Users"

References & Sources

  • Red Hat - “Model Context Protocol (MCP): Understanding security risks and controls”
  • Cisco - “AI Model Context Protocol (MCP) and Security”

Resource access control bypass vulnerabilities can lead to unauthorized access to sensitive data and critical system components.