Machine learning model security is not discussed enough. In serverless GPU–attached environments, block storage solutions like S3 are dependable for persisting your model files. Other than the URI, no other relevant information regarding the model file is saved in the source code.
This exposes an interesting angle to potentially attack an ML system in production. An exposed API key or backdoor could allow hackers to replace a model file with their own. Below we’ll talk about why we can’t trust models coming from untrusted sources. We will also demonstrate a quick and simple process to authenticate models before loading them into memory.
What are the security implications?
Using open-source tools like TensorFlow potentially exposes your platform to cyber attacks. Even though open-source communities are known to quickly patch up bugs, this time delta may be more than enough time for hackers to initiate an attack or drastically affect business operations.
If your models are analyzing sensitive information like credit card information for fraud detection or scanning legal documents to help with discovery for a court case, hackers could use an exploit to export this information back to themselves.
The question of “why models haven’t been more protected than before now” has a trivial answer. Like with most emerging technologies, most companies do not or cannot determine what these exploits can be. Therefore as the industry matures, these security measures need to be implemented quickly, especially for models that process highly sensitive data.
According to TensorFlow’s official documentation that can be found here, TensorFlow models are basically programs and aren’t sandboxed within TensorFlow. A sandboxed application wouldn’t have access to files outside its environment and wouldn’t be able to communicate over the network. As it is, TensorFlow can read and write files, send and receive data over the network, and spawn additional processes, all of which are potentially vulnerable to attack.
The documentation summarizes that “TensorFlow models are programs, and need to be treated as such from a security perspective.”
Authenticating model metrics
Another place where authentication can take place is during continuous integration, where metrics like F1 scores are calculated. This will ensure that the model being tested in CI and the model being deployed in production are the same. Authenticating models prevents data scientists from accidentally overwriting models files and prevents fraudulent models getting into production.
Authentication by computing model hash
Model inference source code is version-controlled via git. Since model files can be huge (several GBs), they must be stored in scalable object/blob storage systems, such as S3. Even though some object-storage services do offer the benefit of keeping track of file hashing, this isn’t the standard case across all services and may not be exposed through the service you’re using to deploy your model.
Simple file-based hash authentication
Because of the potential for model-tampering, it makes sense to calculate the model file hash right after training, and hard-code this into the source code to prevent model file-tampering in flight. This will allow the inference service to verify the model file during runtime, before executing any TensorFlow model code. This is especially true when the only thing hard-coded in the model file is the filename in the source code.
Advanced weight-based hash authentication
Another way to calculate hashes is to use the weights that are provided in model files. The benefit to this approach is that it would be independent of model format and would work across different frameworks.
Fingerprinting models in this approach would provide consistency, reliability, and reproducibility, and protect an ML system from vulnerabilities.
Model authentication demonstration on Algorithmia
We have implemented the simple file-based hash authentication method into our Jupyter notebook. The example trains a simple MNIST model, saves and calculates the hash of the model, deploys the model with the hash, and runs model authentication at runtime before running the model.
Ensure your ML models in production haven’t been hotswapped without anyone noticing.
Model security with Algorithmia
As machine learning becomes part of standard software development, vulnerabilities and new methods of attack are surfacing. Fortunately, Algorithmia has built-in security features to prevent model tampering and we are committed to stewarding these practices in the enterprise for everyone to benefit from. Algorithmia aims to empower every organization to achieve its full potential through the use of artificial intelligence and machine learning.
Read more about ML security
Adversarial Examples for Malware Protection (Patrick McDaniel)
Federated learning and securing data (Digitalist)