If malware via monitor cables is a matter of national security, this might be the gadget for you
- Reference: 1776941111
- News link: https://www.theregister.co.uk/2026/04/23/ncscs_first_foray_into_commercial/
- Source link:
Called SilentGlass, the small gadget's intellectual property is courtesy of the UK's National Cyber Security Centre (NCSC), and the signals intelligence agency licensed it out to UK-based Goldilock Labs to make it commercially available to all businesses and consumers.
SilentGlass is the NCSC's first branded device to hit the market. Announced publicly on Wednesday, the HDMI and DisplayPort-compatible device has already been deployed across "government estates," for several years and is capable of protecting "most high-threat environments."
[1]
Naturally, The Register had a bunch of questions, but the NCSC refused to answer any.
[2]
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Through the powers that be, however, we are reliably informed that beyond the information included in the NCSC's blog, these devices are equipped with hardware that identifies malicious traffic in the data channel, blocking the transfer between computer and display.
We're also told that the SilentGlass gizmos are threat-agnostic, meaning they are capable of detecting any kind of nastiness and preventing it from reaching and ultimately altering or manipulating a display. Anything potentially malicious that travels between HDMI or DisplayPort connections and a monitor is blocked.
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You might be thinking "it's not every day we hear about monitors being pwned via HDMI," and you'd be right.
You wouldn't be alone either. Since the NCSC announced SilentGlass, infoseccers have taken to social media to [5]question the need for this device .
However, it is understood there are legitimate attack paths that are both applicable to modern environments and have been abused by known attackers.
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Very little exists in the research literature about these kinds of attacks. A team based out of Montevideo's Universidad de la República [7]published findings in 2024 about the potential for highly technical individuals to intercept the electromagnetic radiation emitted from HDMI cables and use deep learning algorithms to reproduce text intended to be displayed on a monitor.
The team called the finding Deep-TEMPEST, an evolution of the [8]TEMPEST analog signal interception phenomenon of yesteryear. But, as with all side-channel attacks, the real-world application is significantly different from a remotely exploitable software bug, for example.
Most organizations probably don't need to worry about highly motivated foreign spies lurking around their cables looking for electromagnetic emissions. However, for those safeguarding highly sensitive data within the context of [9]critical national infrastructure operators, it's potentially a slightly more credible threat.
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NCSC's SilentGlass HDMI device – Image courtesy of the NCSC
In any case, SilentGlass devices are available to anyone who wishes to purchase one, starting today.
Attendees of Black Hat or 44con back in 2012 may also remember NCC Group's presentations about the potential for exploiting vulnerabilities in HDMI's [11]EDID and CEC parsers , as well as [12]CDC and NEC protocols .
Again, these are fringe cases of which we hear very little from real-world scenarios, outside a conference keynote.
Despite the lack of published cases of these attacks, the NCSC believes external computer monitors are "a hugely attractive target" for adversaries, particularly those with an espionage focus.
It did not mention China specifically, although that is the country most often associated with cyberespionage, in the context of the UK's four main adversaries - China, Russia, Iran, and North Korea.
The timing of the launch also coincides with the agency's CEO, Richard Horne, [13]declaring China "a peer competitor in cyberspace ," within the context of a steady rate of nationally significant cyberattacks directed at the UK by nation-states.
The org also said such attacks can be effective if the people behind them are looking to cause disruption, or generate some financial gains, which essentially implicates each of the other three countries.
Ollie Whitehouse, the NCSC's CTO, said: "Display screens and monitors are everywhere in modern business environments, and the SilentGlass device will help protect previously vulnerable IT infrastructure with unprecedented ease.
"Its development and commercialisation shows the impact that the NCSC can have, alongside industry partners, with an affordable and effective product now globally available.
"By helping to launch a UK company onto the global market with this world-class innovation, we are breaking new ground and helping to strengthen national prosperity."
NCSC gave Goldilock Labs, in partnership with Sony UK, the license to produce and sell SilentGlass, which comes as separate devices - one for HDMI and another for DisplayPort, each protecting one cable only.
[14]Pass the key, passwords have passed their sell-by date
[15]Iran intelligence backdoored US bank, airport, software outfit networks
[16]Five Eyes warn: Patch your Cisco SD-WAN or risk root takeover
[17]Healthcare security: Write login details on whiteboard, hope for the best
The NCSC wouldn't tell us the price, so we're waiting on Golidlock to tell us more information on that front.
Stephen Kines, co-founder of Goldilock Labs, said the device meets a security problem that to date has been "widely overlooked," as many have not viewed HDMI and DisplayPort connections as a serious security boundary.
"What was once confined to national security environments is now being applied with a low-cost, easy-to-deploy solution for CNI and businesses where the same risks exist," he said.
"SilentGlass is the first step in a wider effort to enforce behaviour at hardware interfaces before it reaches complex software. It reflects a shift toward treating physical connectivity as a point of control rather than an assumed trust boundary." ®
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[2] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/front&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44aepCI-ifw2c4CIwlp2BONgAAAAQ&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/front&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33aepCI-ifw2c4CIwlp2BONgAAAAQ&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/front&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44aepCI-ifw2c4CIwlp2BONgAAAAQ&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[5] https://x.com/ScottMcGready/status/2047221720491172307
[6] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_security/front&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33aepCI-ifw2c4CIwlp2BONgAAAAQ&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[7] https://arxiv.org/abs/2407.09717
[8] https://www.theregister.com/2011/03/10/through_metal_comms_n_power_reinvented/
[9] https://www.theregister.com/2026/01/19/dont_underestimate_prorussia_hacktivists_warns/
[10] https://regmedia.co.uk/2026/04/23/silentglass_hdmi_image.jpg
[11] https://media.blackhat.com/bh-eu-12/Davis/bh-eu-12-Davis-HDMI-Slides.pdf
[12] https://www.nccgroup.com/research/what-the-hec-security-implications-of-hdmi-ethernet-channel-and-other-related-protocols/
[13] https://www.theregister.com/2026/04/21/ncsc_chinas_cyberattacks_uk/
[14] https://www.theregister.com/2026/04/23/ncsc_passkey_tech_now_reliable/
[15] https://www.theregister.com/2026/03/05/mudywater_backdoor_us_networks/
[16] https://www.theregister.com/2026/02/26/five_eyes_cisco_sdwan/
[17] https://www.theregister.com/2026/02/19/human_whiteboard_bork/
[18] https://whitepapers.theregister.com/
Well - if the device is going to remain in any way relevant, then it's firmware would (presumably) need to be updateable. There's your access point for telemetry to the mothership, backdoor snooping, and potential uber-hacker access point all in one. :D
Who says it has firmware? Could be an RF choke in a box for all we know.
4k120 and VRR?
Sounds overkill for office, but 120 Hz is nice to work with. Moving windows is so fluent, and it feels faster on click reaction (exception: Windows 11 UI). And VRR just "'cause duuuude! Of course VRR!"
(Oh, VRR = Variable Refresh Rate, nvidia G-Sync for example)
coax?
The HDMI maximum power is about 291mW. That will radiate. How far , possibly a mile. If people have a good aerial possibly more. The aerial is not discrete.
A coaxial shell would be an answer.
A metal mesh in front of the monitor screen would help.
All of this require close proximity to the building. Civil servants look out the windows.
Re: coax?
HDMI cables are already shielded. At least the good ones are,but probably monitors are leaky, too, and not very well shielded. About this whole idea, what about HDCP? HDMI data should be encrypted by HDCP, to stop us pesky pirates from copying DRM encumbered shit (it seems it's not working as intended, but I digress). So HDMI leaking EM signals should be encrypted, too, I suppose. Picture those pesky Chinese government hackers being thwarted by Hollywood's DRM scheme, LOL.
Re: coax?
I was assuming it was signal capturing. For malware in a secure area i would expect IT or BOFH to keep the network clean.
Re: coax?
about 291mW. That will radiate. How far , possibly a mile.
Voyager 1 has 100x that power, and manages 15bn km, it all depends on the antennae...
I read it differently.
What I was looking at was some form of malware that could be uploaded to a monitor through the interface to infect another machine when it is connected to the screen. Considering that hdmi and usbc both support networking natively, it seems that that could be an overlooked vector. Go to a coworking space or similar and connect to a monitor, come home with a nice piece of malware.
I'm thinking more of a monitor that has been made specifically for spying, not one that has been pwned. I'd say that a "normal" monitor does not have enough capabilities (memory, etc) to contain a malware injection tool. But what about a malicious monitor, built for the job? It could work, exactly as malicious USB power supplies.
But if we come to this, what about printers, mice, keyboards, and every other usb device that is not a battery charger? The need to communicate, you cannot simply cut them off. To sum it up, I think that a monitor is quite an unusual attack vector. But maybe it's a good one exactly because it's unusual. Nobody expects the Spanish Inquisition.
> The Register had a bunch of questions, but the NCSC refused to answer any.
Until NCSC tell us what this thing is, how it works and what it protects against it lies somewhere between snake oil and spyware.
Exactly. Suppose these devices contain a cellular modem and they are actually made to spy on your hdmi data going through.
If they are for sale, I fully expect some security researchers to be doing a tear down very soon.
I wonder what ifixit's repairability score will be?
The sales promises add credence to this possibility. They can't tell us what can actually be done over an HDMI cable, but they can promise that their device blocks all the threats. Given the complexity of HDMI as an interface, I can believe that there are problems in HDMI stacks which could be exploited, and if you knew about them, then a device that looks for them and blocks them would guard against those threats although one that looks for them and sounds an alarm would be more useful. But that wouldn't be threat-agnostic unless it simply blocked some channels, and those channels presumably have a point or you could block them yourself. Maybe it's as simple as disconnecting some things that they assume people buying this, who are probably using monitors in an office environment, probably aren't using, assuming that those pathways could be abused somehow.
But it also protects against tigers and ice giants! Do you want your (hypothetical) children to be eaten by tigers and ice giants?
New target
So now bad actors will have to use a Mythos type of setup to discover any vulnerabilities in SilentGlass.
Goldilocks - just right, or too good to be true?
these devices are equipped with hardware that identifies malicious traffic in the data channel, blocking the transfer between computer and display.
I'm thinking that it's a bit too late by then....
We're also told that the SilentGlass gizmos are threat-agnostic, meaning they are capable of detecting any kind of nastiness
Checks calendar - nope, April 1st was a while ago.
Ignores obvious comment about filtering out anything from/about the US Government.
Wonders how they can detect any kind of nastiness - including those not yet invented. And how it can let through all the stuff that you want, without labelling any of it "nasty".
Thinks we must be getting into Godel/Turing incompleteness/undecidability territory there.
Then remembers that Goldilocks is a fairy tale.
What is This?
Another solution looking for a problem!?.....
Device blocks malicious traffic between computer and display :o
> .. we are reliably informed .. these devices are equipped with hardware that identifies malicious traffic in the data channel, blocking the transfer between computer and display.
So, it sends all your traffic back to GCHQ.
My 2 penneth
The use case is probably using the monitor as an Exfil channel, similar to all those let's use fans or LEDs, or something else that exists, to send data to a remote receiver from an air gapped network
It will be a kill anything outside of the visible spectrum type filter
And I am sure the NCSC wouldn't have baked in the ability for them to have a nose at what's going through it either I expect?