# Attacks On NN Proxies

I’m working on a way of controlling arbitrary physical systems using low energy inputs. The idea is to create a NN (neural network) model that emulates the real world system, develop adversarial attacks against the NN model (which I call the proxy for the real system) and apply those attacks against the real system.

When I say “system”, I’m imagining a stock and flow system or similar, as described here, which has external inputs and outputs, and dynamic internal behavior. By observing inputs and outputs, a NN should be able to emulate the behavior of the system with some degree of accuracy.

A toy example is attacks on a mass spring system. First, create a simple simulation of a mass spring system, which can be given little nudges at every time step. This is the “real” system that we want to attack. In this example, let’s say our goal is to maximize the energy in the system after 10 seconds of simulation. A recurrent neural network (RNN) is trained to behave the same as the mass spring system. Next, adversarial inputs are create against the model. If the RNN model is perfect, then the result should be a wave at resonance of the real system, which would maximize our objective for both the mass spring system and the proxy. More likely, however, is that the RNN would have weaknesses besides those inherent to the real system, and would the adversarial example’s resulting behavior on the real system would be used as a training run. Iterating this process might lead to an RNN the emulates the real model so accurately that attacks on the proxy always transfer to the real model.

This is the experiment I’m working on implementing right now, but learning Autograd frameworks is difficult.

Should I succeed at this, the next step is to apply this technique to complicated coupled mass spring systems, and see how it works with chaotic behavior, like in a double pendulum or three body gravitational system.

Imagine doing this for a three body system, and learning a policy for a tiny booster on an asteroid that could force the ejection of the largest body into deep space. Or an attack on a global trading network to cause a flash crash. How possible either is these is is up for debate but there’s no harm in dreaming.

This technique almost sounds like a variation on reinforcement learning, but with a different starting point. I do believe it will work on mechanical systems (I won’t know until I do experiments) but it’s hard to say if it could work on video games or biological systems. What if you could train on audio input to human ears as system input with fMRI data as system behavior, and tried to maximize activation in a part of the brain? Could it be trained to create hypnotic or physiologically powerful audio? Speculating is fun but it’s pointless until I make a toy model showing that the concept is sound.

There are some things where this would simply not work. For instance, it would probably be very poor at Mario… I think. Actually I have no idea.

## Update Dec 12

I have made a RNN to emulate a spring, next is the task of creating adversarial examples for it and applying them to the actual spring system. I realize how trick training RNN’s is. So far I am training it on several timesteps of the real spring, and having it predict the next state of the spring. If it’s run on its own input, is creates oscillating waves that look a lot like the spring but contain occasional errors and don’t stay fixed at the starting point.

The red and purple lines are displacement and velocity, and the other horizontal lines are constants such as the spring constant and mass. I am very eager to apply adversarial attacks to this model, and find ways of securing it against adversarial attacks in such a way that adversarial attacks that work in this model also work on a real mass spring system.

It’s also quite interesting to see a fuzzy model of a not fuzzy at all phenomenon, I wonder how similar this is to my physics intuitions.