Missing Integrity Controls

Category: Protocol Vulnerabilities
Severity: High
MITRE ATT&CK Mapping: T1565 (Data Manipulation)

Description

Lack of message signing or verification mechanisms allowing message tampering, enabling attackers to modify MCP messages in transit without detection.

Technical Details

Attack Vector

  • Message tampering attacks
  • Man-in-the-middle attacks
  • Protocol message modification
  • Communication integrity bypass

Common Techniques

  • Message interception and modification
  • Protocol message injection
  • Communication tampering
  • Integrity bypass

Impact

  • Message Tampering: Unauthorized modification of MCP messages
  • Data Integrity Loss: Compromised message integrity
  • Communication Compromise: Compromised communication channels
  • Trust Erosion: Loss of trust in communication integrity

Detection Methods

Message Analysis

  • Monitor message integrity
  • Detect message modifications
  • Analyze message patterns
  • Monitor communication integrity

Protocol Monitoring

  • Monitor protocol communications
  • Track message integrity
  • Detect protocol tampering
  • Analyze protocol security

Mitigation Strategies

Integrity Protection

  • Implement message signing
  • Use message authentication codes
  • Deploy integrity verification
  • Monitor message integrity

Communication Security

  • Implement secure communications
  • Use encrypted channels
  • Deploy integrity controls
  • Monitor communication security

Real-World Examples

Example 1: Message Tampering

# Original message
message = {
    "type": "tool_call",
    "tool": "file_reader",
    "params": {"file": "document.txt"}
}

# Tampered message (no integrity check)
message = {
    "type": "tool_call",
    "tool": "file_reader",
    "params": {"file": "/etc/passwd"}  # Modified parameter
}

Example 2: Protocol Message Injection

# Legitimate message flow
def send_message(message):
    # No integrity protection
    transmit_message(message)

# Attacker injects malicious message
malicious_message = {
    "type": "admin_command",
    "command": "delete_all_users"
}
send_message(malicious_message)  # Injected without detection

Example 3: Communication Tampering

# Vulnerable communication without integrity
def communicate(data):
    # No message signing or verification
    response = send_to_server(data)
    return response

# Attacker intercepts and modifies response
# No way to detect tampering

References & Sources

  • Equixly - “MCP Servers: The New Security Nightmare”
  • Red Hat - “Model Context Protocol (MCP): Understanding security risks and controls”

Missing integrity controls enable message tampering attacks that can compromise the entire MCP communication system.