# PIXHELL Attack: Leaking Information from Air-Gap Computers via `Singing Pixels'

Source: https://arxiv.org/abs/2409.04930
Kiwi News: https://news.kiwistand.com/stories/PIXHELL-Attack-Leaking-Information-from-Air-Gap-Computers-via-Singing-Pixels?index=0x66e5699b86ccffd1a549e35f9da98ebd19338ec74f05c34da6b2d0b9e2459cd3a0b7b57d
Submitted by misha on 2024-09-14 UTC, 1 upvote, 0 comments

## Summary

PIXHELL is a covert channel attack that leaks data from air-gapped and audio-gapped computers through acoustic noise generated by screen pixels, without requiring audio hardware or loudspeakers. Malware generates crafted pixel patterns that produce noise in the 0 to 22 kHz range, exploiting sound from the coils and capacitors that control screen frequencies. According to the paper's tests, textual and binary data can be exfiltrated at a distance of 2 meters via sound modulated from LCD screens. The paper also covers low-brightness patterns that appear like turned-off screens for evasion and proposes countermeasures.

## Article

PIXHELL Attack: Leaking Sensitive Information from Air-Gap Computers via `Singing Pixels'

Authors: Mordechai Guri

Air-gapped systems are disconnected from the Internet and other networks because they contain or process sensitive data. However, it is known that attackers can use computer speakers to leak data via sound to circumvent the air-gap defense. To cope with this threat, when highly sensitive data is involved, the prohibition of loudspeakers or audio hardware might be enforced. This measure is known as an `audio gap'.

In this paper, we present PIXHELL, a new type of covert channel attack allowing hackers to leak information via noise generated by the pixels on the screen. No audio hardware or loudspeakers is required. Malware in the air-gap and audio-gap computers generates crafted pixel patterns that produce noise in the frequency range of 0 - 22 kHz. The malicious code exploits the sound generated by coils and capacitors to control the frequencies emanating from the screen. Acoustic signals can encode and transmit sensitive information. We present the adversarial attack model, cover related work, and provide technical background. We discuss bitmap generation and correlated acoustic signals and provide implementation details on the modulation and demodulation process. We evaluated the covert channel on various screens and tested it with different types of information. We also discuss \textit{evasion and stealth} using low-brightness patterns that appear like black, turned-off screens. Finally, we propose a set of countermeasures. Our test shows that with a PIXHELL attack, textual and binary data can be exfiltrated from air-gapped, audio-gapped computers at a distance of 2m via sound modulated from LCD screens.