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August 28, 2020

APL and the Intelligence Community Tackle Malware in the Age of AI

Demonstration of machine-vision Trojan. TrojAI researcher (not teddy bear) Neil Fendley demonstrates a backdoor he embedded in the deep network weights of a common network used for object detection and classification. The network classifies dozens of objects correctly, but when a person puts the embedded trigger — in this case the black and white target sticker — on their clothes, the system immediately misidentifies them as a teddy bear. The backdoor is very specific: when placed on other objects — like the chair — the trigger has no impact, and the network makes correct classifications.

Credit: Johns Hopkins APL


Demonstration of reinforcement-learning agent Trojan. Reinforcement learning models, like the one shown here trained to play Atari Boxing, are also subject to difficult-to-detect Trojan attacks.

Credit: Johns Hopkins APL

Today’s malware can be vicious. Malicious code hidden deep within our programs and applications can be engineered to steal passwords and personal information, lock people and companies out of their systems and data until a ransom is paid, or even just deliver unwanted advertisements.

The good news is that detection and virus scanning have come a long way, and hundreds of thousands of pieces of malware are “caught” every day.

Until now, software analysts and engineers have had many of the tools they need to deal with threats. But as more commercial and government systems become intelligent and include components with deep neural networks, the balance of power is shifting.

“Right now, it looks to be a very asymmetric problem: easy to insert vulnerabilities, often impossible to detect,” explained Mike Wolmetz, who manages human and machine intelligence research at the Johns Hopkins Applied Physics Laboratory (APL), in Laurel, Maryland.

“Embedding malicious or adversarial behaviors in deep networks is relatively straightforward,” he continued. “As an early proof of concept last year, one of our researchers was able to train a backdoor into our copy of a popular deep network in a matter of hours. It wasn’t very malicious — it caused the machine-vision system to misclassify people who wore a particular trigger as teddy bears — but it could have been if engineered by an adversary. Unfortunately, this backdoor that took no time to embed in the network’s code is completely undetectable, ​for now.”

Researchers at APL and across the country are quickly working to change that.

The deep network architectures now critical to many intelligent systems — from cars and personal assistants to industrial robots and HVAC systems — are key to the extraordinary performance of modern AI, but the only guaranteed method for preventing malware is to completely secure the AI supply chain.

“The AI supply chain will probably always have holes,” explained Kiran Karra, a research engineer in APL’s Research and Exploratory Development Department. ”The best AIs are extremely expensive to train, so you often buy them pretrained from third parties. Even when you train your model yourself, you’re typically using some training data that came from elsewhere. These are two prime opportunities to introduce Trojans.”

APL scientists are working with the intelligence community on an Intelligence Advanced Research Projects Activity (IARPA) program called TrojAI that is funding research on defenses for “training-time attacks,” like backdoors or Trojans — vulnerabilities that deep networks are exposed to during the AI training process. The objective of the TrojAI program is to develop fundamentally new methods to inspect AIs for Trojans.

“The Trojan vulnerability is different from ‘test-time attacks’ that try to fool AIs without access to the model during training, such as those used to fool driverless cars using stickers or masking tape,” Karra said. “In test-time attacks, someone takes a neural network, adds some noise to the input image and classifies it as something completely different. These kinds of attacks happen after the model has been trained, during ‘inference​’ or ‘test time.’ There is a great deal of focus on that problem, but not as much focus has been placed on Trojan attacks.”

Karra and fellow TrojAI researchers Chace Ashcraft and Neil Fendley have been working closely with IARPA to rapidly develop methods for evaluating how well new algorithms can detect Trojans in deep neural networks. That work includes different classes of network architectures, as well as AIs that have functions like recognizing images, understanding text or playing games.

The team has already developed an open-source set of Python tools capable of generating triggered or poisoned datasets and associated deep-learning models with Trojans at scale. They describe their work in “The TrojAI Software Framework: An Open Source Tool for Embedding Trojans into Deep Learning Models,” to be presented at the Robustness of AI Systems Against Adversarial Attacks (RAISA3) workshop on Aug. 29.

“We used the framework to generate a large set of Trojaned classifiers and demonstrated the capability to produce a Trojaned reinforcement-learning model using vector observations,” Karra said. “This will help researchers better understand the effects of various parameters and configurations on Trojaned models, and that will, in turn, help to test new Trojan detection methods.”

These tools have been transitioned to the National Institute of Standards and Technology, which has scaled them up and deployed them to continuously evaluate Trojan detection algorithms developed by TrojAI performers and the general public. Progress against increasingly challenging Trojan detection scenarios can be tracked on a public leaderboard.

In parallel, APL researchers are working on other approaches for assuring AIs, from techniques to sanitize deep networks that may have undetectable Trojans trained into their weights, to formal methods to guarantee the reliability of deep networks, as presented at the Workshop on Formal Methods for ML-Enabled Autonomous Systems in July.

According to Wolmetz, while AI increasingly meets or exceeds human performance across many tasks, contexts and modalities, adversarial attacks are growing in sophistication and efficacy. For every new national security application of AI that comes online, critical vulnerabilities closely follow.

“No narrow or weak AI can be expected to survive contact with an adversary,” Wolmetz said. “In the future, we’ll have more general AIs with fewer vulnerabilities, but also more intelligent attacks. As we invent the future of intelligent systems for national security applications, we have to carefully consider how this cat-and-mouse game will evolve.”

Beyond TrojAI, APL conducts basic and applied research in AI for the national security community to bring intelligent systems to every mission.

Media contact: Paulette Campbell, 240-228-6792, Paulette.Campbell@jhuapl.edu

The Applied Physics Laboratory, a not-for-profit division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit www.jhuapl.edu.