A Wolf in Sheep's Clothing: Spreading Deadly Pathogens Under the Disguise of Popular Music

TL;DR

This paper reveals that malicious music can exploit resonant frequencies of differential pressure sensors in negative pressure rooms, enabling stealthy attacks that could cause pathogen leaks, with experiments validating the vulnerability.

Contribution

It uncovers the resonant frequency vulnerability of DPSs in NPRs and demonstrates a novel non-invasive attack method using malicious music to manipulate pressure readings.

Findings

Resonant frequencies of DPSs are in the audible range.

Malicious music can induce pressure overshoot in DPSs.

The attack can cause NPRs to lose negative pressure, risking pathogen leaks.

Abstract

A Negative Pressure Room (NPR) is an essential requirement by the Bio-Safety Levels (BSLs) in biolabs or infectious-control hospitals to prevent deadly pathogens from being leaked from the facility. An NPR maintains a negative pressure inside with respect to the outside reference space so that microbes are contained inside of an NPR. Nowadays, differential pressure sensors (DPSs) are utilized by the Building Management Systems (BMSs) to control and monitor the negative pressure in an NPR. This paper demonstrates a non-invasive and stealthy attack on NPRs by spoofing a DPS at its resonant frequency. Our contributions are: (1) We show that DPSs used in NPRs typically have resonant frequencies in the audible range. (2) We use this finding to design malicious music to create resonance in DPSs, resulting in an overshooting in the DPS's normal pressure readings. (3) We show how the resonance in DPSs can fool the BMSs so that the NPR turns its negative pressure to a positive one, causing a potential \textit{leak} of deadly microbes from NPRs. We do experiments on 8 DPSs from 5 different manufacturers to evaluate their resonant frequencies considering the sampling tube length and find resonance in 6 DPSs. We can achieve a 2.5 Pa change in negative pressure from a $\sim$7 cm distance when a sampling tube is not present and from a $\sim$2.5 cm distance for a 1 m sampling tube length. We also introduce an interval-time variation approach for an adversarial control over the negative pressure and show that the \textit{forged} pressure can be varied within 12 - 33 Pa. Our attack is also capable of attacking multiple NPRs simultaneously. Moreover, we demonstrate our attack at a real-world NPR located in an anonymous bioresearch facility, which is FDA approved and follows CDC guidelines. We also provide countermeasures to prevent the attack.