Researchers from the National University of Singapore and Yonsei University in the Republic of Korea have invented a device that can detect whether malware has access to a laptop microphone without permission.
The prototype device, codenamed TickTock, described in a paper (opens in new tab) titled “TickTock: Detecting Microphone Status in Laptops Using Electromagnetic Clock Leakage,” is so named because of the way it monitors electromagnetic (EM) leakage from laptop microphone clock signals.
The five brains behind the development – Soundarya Ramesh, Ghozali Suhariyanto Hadi, Sihun Yang, Mun Choon Chan and Jun Han – call TickTock one of the first “adequate solutions” to malware attacks that use microphones, a definite privacy advantage.
Microphones and malware
Misuse of microphones in laptops by cyberattacks has so far been more difficult to combat than attacks based on webcams, which can be thwarted simply by placing a slider or piece of tape over the lens.
The latest and best apple laptops will disable the microphone when the lid is closed, Dell has Linux drivers that support user privacy, Windows 10 and macOS 12 visibly indicate microphone activation, and Purism’s Librem 5 USA, a privacy-focused smartphone, features three hardware switches. However, not all devices benefit from these types of protection.
Users who prefer hardware-based solutions, given that malware can compromise software-based security features, may need to stick with TickTock. The final form of the device, its developers say, could be a simple USB drive, perfect for business laptops or mobile workstations.
Testing TickTock on thirty laptops, the researchers successfully and consistently identified microphone on/off status on twenty-seven of them. The paper claims of this data that the new device “correctly identifies the microphone recording with high true positive and negative rates”.
However, the paper also acknowledges that TickTock needs more time in development because the device was unable to detect microphone signals in all three Apple Macbooks tested. Obviously, the aluminum housing and short flexible cables reduce EM leakage to undetectable levels.
In addition, while TickTock was shown to work well on laptops with built-in recording hardware, it fared less well on smartphones, tablets, smart speakers, and USB webcams. In these scenarios, it was only able to detect microphone clock rates in 21 out of 40 devices.
The researchers cite a number of reasons for this, including the use of analog microphones instead of digital devices without power constraints that do not cut off clock frequencies when not in use, and smaller form factors causing “reduced EM leakage in the lower radio frequencies “.
However, the researchers will continue to develop TickTock, hoping in the future to “identify access to other sensors, including cameras and inertial measurement unit (IMU) sensors.”
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