T07 · Tool Hijacking and Spoofing
Error
- Location
scripts/office/soffice.py:24- Finding
Predictable Temporary Shared Library Enables LD_PRELOAD Tool Hijacking
- Content
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dict: env = os.environ.copy() env["SAL_USE_VCLPLUGIN"] = "svp" if _needs_shim(): shim = _ensure_shim() env["LD_PRELOAD"] = str(shim) return env _SHIM_SO = Path(tempfile.gettempdir()) / "lo_socket_shim.so" def _needs_shim() -> bool: try: s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) s.close() return False except OSError: return True def _ensure_shim() -> Path: if _SHIM_SO.exists(): return _SHIM_SO src = Path(tempfile.gettempdir()) / "lo_socket_shim.c" src.write_text(_SHIM_SOURCE) subprocess.run( ["gcc", "-shared", "-fPIC", "-o", str(_SHIM_SO), str(src), "-ldl"], check=True, capture_output=True, ) src.unlink() return _SHIM_SO ``` ### Technical Analysis The generated shared library uses the fixed path `/tmp/lo_socket_shim.so`. If that path already exists, `_ensure_shim()` accepts it without validating: - File ownership - File permissions - Whether it is a regular file or symbolic link - Its cryptographic digest or expected contents - Whether it was produced by the current process When UNIX-domain socket creation fails, `get_soffice_env()` places this unverified file in `LD_PRELOAD`. The dynamic loader will load the library before starting LibreOffice, giving its initialization routines and intercepted functions native code execution inside the `soffice` process. The subprocess call itself does not use a shell and is not vulnerable to shell command injection. The vulnerability instead arises from trusting a predictable, cross-process temporary artifact and explicitly preloading it. ### Attack Path 1. An attacker with access to the same host or shared t ...[truncated 1252 chars]- Remediation
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