# Security Considerations for Lambda-MCP
This document outlines key security considerations for the Lambda-MCP implementation, including lessons learned from analyzing similar projects like [MCP2Lambda](https://github.com/danilop/MCP2Lambda).
## Potential Security Risks
### 1. Function Execution Controls
**Risk**: Allowing LLMs to execute arbitrary Lambda functions could lead to unintended access and actions.
**Mitigation**:
- Each Lambda-MCP server should handle one specific API/service, reducing the attack surface
- Do not implement a generic Lambda invoker like MCP2Lambda does
- Implement input validation for all parameters passed to underlying services
### 2. Parameter Validation
**Risk**: Without proper validation, parameters passed to underlying services could be used for injection attacks.
**Mitigation**:
- Implement strict validation of all input parameters
- Use type checking and schema validation
- Sanitize inputs before passing to external services
- Consider using AWS WAF for API Gateway endpoints
### 3. Authentication and Authorization
**Risk**: Unauthorized access to the Lambda-MCP server could lead to data exposure.
**Mitigation**:
- Implement robust authentication for API Gateway endpoints
- Use JWT tokens or API keys for authentication
- Consider implementing CORS policies
- Utilize AWS IAM for precise permission controls
### 4. Data Exposure
**Risk**: Returning excessive information could lead to data leakage.
**Mitigation**:
- Only return necessary information to the MCP client
- Implement response filtering
- Log sensitive operations
- Consider implementing data redaction for sensitive information
## Secure Implementation Patterns
### 1. Principle of Least Privilege
Each Lambda-MCP server should have the minimum permissions necessary to perform its intended function. For example:
- A GraphQL MCP server should only have permissions to access the specific GraphQL endpoint
- An Elasticsearch MCP server should only have permissions to perform authorized searches
### 2. Input/Output Sanitization
- Always validate and sanitize inputs before processing
- Filter outputs to prevent information leakage
- Use JSON schema validation for structured inputs
### 3. Single-Purpose Design
Our approach of building separate, focused MCP servers (rather than a generic Lambda invoker) provides inherent security benefits:
- Reduced attack surface for each server
- Easier to reason about security implications
- More appropriate permission scoping
### 4. Defense in Depth
- Implement multiple layers of security controls
- Add rate limiting to prevent abuse
- Set up monitoring and alerting for suspicious activity
- Consider implementing circuit breakers for failing services
## Security Testing
Before deploying Lambda-MCP servers to production, consider:
- Conducting security testing of the implementation
- Performing prompt injection testing to see if LLMs can be tricked into malicious actions
- Testing rate limiting and access controls
- Reviewing IAM permissions for over-privileged roles
