Thermal Steganography: A New Way to Steal Data from Air-Gapped Computers Using Heat and Fan Noise

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This is an unedited manuscript accepted for publication and provided as an Article in Press for early access at the author’s request. The article will undergo copyediting, typesetting, and galley proof review before final publication. Please be aware that errors may be identified during production that could affect the content. All legal disclaimers of the journal apply.

Year : 2026 | Volume : 04 | Issue : 02 | Page :
    By

    Kaushal D Jani,

  • Bhargav Rajyagor,

  1. Assistant Professor, Department of Computer Application, Noble University, Junagadh, Gujarat, India
  2. Associate Professor, Department of Computer Application, Noble University, Junagadh, Gujarat, India

Abstract

Nowadays, high-security computers are “air-gapped,” meaning they are not connected to the internet to prevent hacking. Cybercriminals are increasingly using direct, physical methods to access and take data instead of relying on internet-based attacks. This paper introduces a new cybersecurity threat called Thermal-Secret. Most existing heat-based attacks are very slow and fail if the room temperature changes. To solve this, we developed a Slope-Based method. Instead of looking at how hot a computer is, we look at how fast the temperature is rising or falling.

In our experiment, we used a special Python script that makes the CPU do heavy math (Matrix Multiplication). This creates a “Heat Signal” that represents binary 1s and 0s. A “1” is sent by making the CPU hot quickly, and a “0” is sent by letting it cool down. We monitored these changes using the computer’s own internal sensors and fan speed data.

Our testing shows that this method is very hard for Antivirus software to detect because it looks like a normal computer task. Even if the computer has strong fans, our “Slope” method can still read the hidden message correctly. This research proves that even if a computer is not on the internet, its heat can be used to leak secret information. We conclude that companies must start “masking” their thermal data to protect themselves from such advanced physical hacking attacks.

Keywords: Air-Gapped Systems, Covert Channels, Thermal Steganography, Differential Slope-Based Modulation, slope-based Steganography

[This article belongs to International Journal of Information Security Engineering ]

How to cite this article:
Kaushal D Jani, Bhargav Rajyagor. Thermal Steganography: A New Way to Steal Data from Air-Gapped Computers Using Heat and Fan Noise. International Journal of Information Security Engineering. 2026; 04(02):-.
How to cite this URL:
Kaushal D Jani, Bhargav Rajyagor. Thermal Steganography: A New Way to Steal Data from Air-Gapped Computers Using Heat and Fan Noise. International Journal of Information Security Engineering. 2026; 04(02):-. Available from: https://journals.stmjournals.com/ijise/article=2026/view=246848


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Regular Issue Subscription Original Research
Volume 04
Issue 02
Received 14/03/2026
Accepted 16/06/2026
Published 17/06/2026
Publication Time 95 Days
13

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