exposed-mcp-server: Exposed MCP JSON-RPC 2.0 API Detection

id: exposed-mcp-server

info:
  name: Exposed MCP JSON-RPC 2.0 API Detection
  author: ivan_wallarm
  severity: unknown
  description: |
    Detects exposed Machine Control Protocol (MCP) servers through JSON-RPC 2.0 API endpoints.
    MCP servers often provide administrative access to AI tools, LLM systems, or other automation infrastructure.
    Exposed MCP interfaces can lead to unauthorized access, information disclosure, and potential system compromise.
    This template tests multiple detection methods including tools/list, rpc.discover, resources/list, and prompts/list.
  metadata:
    verified: true
    max-request: 10
  reference:
    - https://jsonrpc.org/specification
    - https://github.com/anthropics/anthropic-tools/tree/main/mcp
    - https://lab.wallarm.com/wallarm-research-nuclei-template-counter-threats-targeting-llm-apps/
  tags: mcp,jsonrpc,devtools,exposure,api,ai,llm,discovery

http:
  - method: POST
    path:
      - "{{BaseURL}}"
      - "{{BaseURL}}/mcp/"

    headers:
      Accept: application/json, text/event-stream
      Content-Type: application/json

    payloads:
      method:
        - rpc.discover
        - rpc.describe
        - rpc.listTools
        - tools/list
        - resources/list
        - prompts/list
        - tool.status
        - tool.help
        - tool.version
        - tool.list

    attack: pitchfork

    body: |
      {
        "jsonrpc": "2.0",
        "method": "{{method}}",
        "params": {},
        "id": 1
      }

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - "jsonrpc"
          - "result"
        condition: and

      - type: regex
        part: body
        regex:
          - "\"available_tools\"\\s*:\\s*\\["
          - "\"name\"\\s*:\\s*\"get_tools\""
          - "\"server_status\"\\s*:\\s*\\{"
          - "\"observatories_by_type\""
          - "\"parameters\"\\s*:\\s*\\{"
          - "\"tools\"\\s*:\\s*\\[.*?\\]"
          - "\"resources\"\\s*:\\s*\\[.*?\\]"
          - "\"prompts\"\\s*:\\s*\\[.*?\\]"

    extractors:
      - type: regex
        part: body
        regex:
          - "\"name\"\\s*:\\s*\"([^\"]+)\""
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