redteam-mcp-auth (Red Team MCP Authentication)

You can run this example with:

npx promptfoo@latest init --example redteam-mcp-auth
cd redteam-mcp-auth

This example demonstrates how to configure authentication for red team evaluations against MCP (Model Context Protocol) servers. It shows OAuth 2.0 client credentials flow for authenticating with remote MCP servers.

Overview

When running red team evaluations against protected MCP servers, you need to configure authentication. This example shows how to set up OAuth authentication in your MCP target configuration.

Configuration

OAuth Authentication

The promptfooconfig.oauth.yaml file demonstrates OAuth 2.0 client credentials flow:

targets:
  - id: mcp
    label: MCP Example
    config:
      enabled: true
      server:
        url: https://example-app.promptfoo.app/mcp/minnow?auth_type=bearer
        auth:
          type: oauth
          grantType: client_credentials
          clientId: '{{env.PROMPTFOO_TARGET_CLIENT_ID}}'
          clientSecret: '{{env.PROMPTFOO_TARGET_CLIENT_SECRET}}'
          tokenUrl: https://example-app.promptfoo.app/oauth/token
          scopes: []

Environment Variables

This example requires the following environment variables:

• PROMPTFOO_TARGET_CLIENT_ID - Your OAuth client ID
• PROMPTFOO_TARGET_CLIENT_SECRET - Your OAuth client secret

NOTE: The values for these environment variables are available upon request.

Running the Example

1. Set up environment variables:

export PROMPTFOO_TARGET_CLIENT_ID=your-client-id
export PROMPTFOO_TARGET_CLIENT_SECRET=your-client-secret

2. Run the red team evaluation:

promptfoo redteam run -c promptfooconfig.oauth.yaml

3. View the results:

promptfoo view

How It Works

OAuth Flow for MCP

When using OAuth authentication with MCP servers:

1. If tokenUrl is not specified, the provider discovers it using RFC 8414 OAuth metadata
2. The MCP provider requests an access token from the tokenUrl using client credentials
3. The token is cached and proactively refreshed before it expires (with a 60-second buffer)
4. The token is added to MCP transport requests as an Authorization: Bearer <token> header
5. If a token expires during an evaluation, the provider automatically reconnects with a fresh token

Token Refresh

The MCP provider implements proactive token refresh:

• Tokens are refreshed 60 seconds before expiration
• Concurrent requests share the same refresh operation (no duplicate token fetches)
• If a 401 error occurs, the provider automatically refreshes and retries

Other Authentication Methods

The MCP provider also supports these authentication types:

Bearer Token

server:
  url: https://mcp-server.example.com
  auth:
    type: bearer
    token: '{{env.MCP_BEARER_TOKEN}}'

Basic Authentication

server:
  url: https://mcp-server.example.com
  auth:
    type: basic
    username: '{{env.MCP_USERNAME}}'
    password: '{{env.MCP_PASSWORD}}'

API Key

server:
  url: https://mcp-server.example.com
  auth:
    type: api_key
    value: '{{env.MCP_API_KEY}}'
    placement: header # or 'query'
    keyName: X-API-Key # header/param name

OAuth Password Grant

server:
  url: https://mcp-server.example.com
  auth:
    type: oauth
    grantType: password
    tokenUrl: https://auth.example.com/token
    username: '{{env.MCP_USERNAME}}'
    password: '{{env.MCP_PASSWORD}}'
    clientId: '{{env.MCP_CLIENT_ID}}' # optional
    clientSecret: '{{env.MCP_CLIENT_SECRET}}' # optional
    scopes: ['read', 'write']

Security Best Practices

• Never commit credentials to version control
• Use environment variables for all sensitive values
• Use the most restrictive scopes necessary for OAuth
• Rotate credentials regularly in production environments

Customizing for Your MCP Server

To use this example with your own MCP server:

1. Update the url to point to your MCP server endpoint
2. Update the tokenUrl for OAuth authentication
3. Set the appropriate environment variables
4. Adjust the redteam.purpose to describe your system
5. Configure the appropriate plugins for your security testing needs

For more information, see the MCP Provider documentation and Red Team documentation.