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[return to "How I discovered a hidden microphone on a Chinese NanoKVM"]
1. tayior+t6[view] [source] 2025-12-06 14:54:59
>>ementa+(OP)
To be fair, the microphone _is_ listed on the specsheet of the LicheeRV Nano

https://wiki.sipeed.com/hardware/en/lichee/RV_Nano/1_intro.h...

I assume they didn't intend to put a mic on the KVM product, but they wanted to make a KVM product, already had this SBC product, which reusing their existing stock of helped keep cost low.

Should they have been more up front about it it? Sure, and it's not great that they had a bunch of security issues in the FW anyway, so not exactly great, but "hidden microphone in a Chinese KVM" lets the mind wander

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2. ndsipa+4d[view] [source] 2025-12-06 15:44:50
>>tayior+t6
It doesn't strike me as that useful to have a hidden microphone in a KVM product as most of the time, they're going to be stuck in server rooms with just lots of fan noise to record.

Far more of an issue would be any kind of keylogger built into the software, which is why it's best to go for devices that support open source software.

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3. Y_Y+mf[view] [source] 2025-12-06 16:04:09
>>ndsipa+4d
just fan noise?

https://arxiv.org/abs/1606.05915

Any signal that you can modulate can be an exfiltration channel, and fan noise is no different.

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4. overfe+bC[view] [source] 2025-12-06 19:04:54
>>Y_Y+mf
> Any signal that you can modulate can be an exfiltration channel, and fan noise is no different.

This KVM has HDMI input and can directly emulate USB mass storage; fan-modulation is the lowest-bandwidth (side-)channel available to the attackers.

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5. nine_k+qH[view] [source] 2025-12-06 19:47:46
>>overfe+bC
You can exfiltrate data from a machine which is not connected to the KVM. A high-security machine may be even air-gapped most of the time, but be physically nearby.
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