T03 · Remote Payload Retrieval and Execution
Error
- Location
- vendor/xhs_api/xhs_utils/common_util.py:66
- Finding
- Remote Server Response Is Compiled and Executed as JavaScript<![CDATA[ ## Vulnerability Details **File Location**: `vendor/xhs_api/xhs_utils/common_util.py:66-99` **Vulnerability Type**: Remote payload retrieval and execution **Risk Level**: High ### Vulnerable Code ```python def fetch_sec_cookies(cookies, headers): """获取 sec_poison_id 和 websectiga""" sec_poison_id = None websectiga = None api = '/api/sec/v1/scripting' data = {"callFrom": "web", "callback": "seccallback"} h = dict(headers) h['content-type'] = 'application/json;charset=UTF-8' sign_h = _generate_xsc(cookies['a1'], api, data) h.update(sign_h) data_str = json.dumps(data, separators=(',', ':'), ensure_ascii=False) try: resp = requests.post( _AS_URL + api, headers=h, cookies=cookies, data=data_str.encode('utf-8'), timeout=REQUEST_TIMEOUT ) res = resp.json() sec_poison_id = res.get('data', {}).get('secPoisonId') jsvmp_code = res.get('data', {}).get('data', '') if jsvmp_code: env = _load_websectiga_env() if env: try: js_code = env + '\n' + jsvmp_code + '\nvar __result = _websectiga_result;' ctx = execjs.compile(js_code) websectiga = ctx.eval('__result') or None except Exception as e: logger.debug(f'websectiga jsvmp execution failed: {e}') except Exception as e: logger.debug(f'fetch sec cookies failed: {e}') return sec_poison_id, websectiga ``` ### Technical Analysis The function retrieves JavaScript from `https://as.xiaohongshu.com/api/sec/v1/scripting`, concatenates the response with a local JavaScript environment, and passes the result to `execjs.compile()`. PyExecJS normally invokes a locally installed JavaScript runtime such as Node.js, so the downloaded payload executes with the privileges and environment of the local Skill process. The effective execu ...[truncated 1373 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove `fetch_sec_cookies()` if it is not required by the documented execution path. 2. Do not compile or evaluate JavaScript supplied in an HTTP response. 3. Replace the remote payload with a locally vendored, readable implementation whose source and hash are pinned and reviewed. 4. If remote execution is operationally unavoidable, verify a cryptographic signature from a separately managed trust root before execution. 5. Execute the signing component in a sandboxed process or container with: - No inherited environment secrets. - No access to cookie or Agent configuration directories. - A read-only filesystem. - No network access after the payload has been obtained. - Strict CPU, memory, and execution-time limits. 6. Add tests that fail if `execjs.compile()` or equivalent evaluation receives network-derived input. ]]>