T09 · Insecure Skill Coding Practices
Error
- Location
scripts/office/soffice.py:28- Finding
Predictable LD_PRELOAD Artifact Enables Local Code Execution
- Content
View full analysis
dict: env = os.environ.copy() env["SAL_USE_VCLPLUGIN"] = "svp" if _needs_shim(): shim = _ensure_shim() env["LD_PRELOAD"] = str(shim) return env def run_soffice(args: list[str], **kwargs) -> subprocess.CompletedProcess: env = get_soffice_env() return subprocess.run(["soffice"] + args, env=env, **kwargs) _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 native shim and its C source are placed at fixed, predictable names in the shared system temporary directory. If `lo_socket_shim.so` already exists, `_ensure_shim()` accepts it without verifying its ownership, permissions, file type, contents, or cryptographic integrity. When `_needs_shim()` detects that an AF_UNIX socket cannot be created, the unverified file is assigned to `LD_PRELOAD`. LibreOffice is then launched with that environment. The operating-system loader executes the constructors and intercepted functions in the supplied shared object before the normal application code. The source and output filenames are also susceptible to symlink and time-of-check/time-of-use attacks because they are written and compiled through sha ...[truncated 1506 chars]- Remediation
View remediation