Brain-Prompt Injection: A New Frontier in BCI Security

Brain-computer interfaces (BCIs) are opening up new possibilities in the space of tool-use agents. But with innovation comes vulnerability. Meet the newest threat: brain-prompt injection. This isn't just a buzzword. It's a real risk where perturbations can manipulate the action route while monitors stay oblivious.

The Vulnerability in BCIs

Decoded neural activity, when turned into authorization channels, exposes BCIs to attacks that can re-route actions. Imagine signal-side perturbations or context-only injections. They sound niche, but the impact? Considerable. In such a setup, route safety isn't about decoder accuracy. It's about what the audit log can actually see.

Audit Contracts: The New Frontier

Enter the Route-Safety Audit Contract. It's not just a fancy term. This contract outlines a minimal log schema and endpoint specification. Why is this important? Because clean agreement on its own doesn't prevent attacks. The secret lies in the audit-schema separation theorem, which breaks down how attackers can manipulate routes.

Calibration and Confirmation

We need more than just accuracy. So, split-conformal calibration is applied as a layer over non-oracle EEG channels. In tests with 5,400 events, they found that an attacker-controllable confirmation channel could break security bounds. A false-accept rate (FAR) of zero at a clean utility of 0.150 for an alpha of 0.005 shows potential. Yet, it shoots up to 0.119 when alpha hits 0.10 under controlled conditions. What does this tell us? Secure calibration isn't just a luxury, it's necessary.

The Bigger Picture

This isn't just a theoretical exercise. In tests, mediation and confirmation layers reduced risks, but they're not foolproof. They don't certify intent, only reduce the probability of attack. With results confirmed across 60 subjects and spanning different architectures like TinyEEGNet and EEGNetV4, the findings are solid. But real-world applications? Still a work in progress.

Here's a question: How far are we willing to push BCIs without addressing these vulnerabilities? The tech may be fascinating, but as always, ship it to testnet first. Always.