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I've been watching videos of scammers being tricked. Frequently, the scammer makes their scam victim install some weird "remote desktop" program claimed to be for tech support purposes. These programs apparently allow the person connecting to the host (victim) computer to "black the screen" so that it becomes impossible for them to see what's being done.

Why would any legitimate "remote desktop" software have such a feature? What non-scam purpose could there be for that?

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    Who says the scammer is installing a "legitimate" RD program?
    – MikeB
    Commented Apr 13, 2021 at 11:43
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    @MikeBrockington: It's easier for a non-tech-savvy scammer to get a customer to download a popular RD program and then grant access to the machine than to host a site from which a customer could download a fake one.
    – supercat
    Commented Apr 13, 2021 at 19:02
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    Wait, "scammers being tricked"?
    – Rafalon
    Commented Apr 14, 2021 at 13:53
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    @Rafalon yes, look up scambaiting
    – foerno
    Commented Apr 14, 2021 at 14:13

3 Answers 3

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So that passers-by cannot see what you are doing on your computer.

If you are connecting remotely to a computer in an office, then everyone could see everything you type and you would not know.

It is a basic, expected, and legitimate feature. (By the way, that's the top 8 remote desktop programs each with a "blank screen" feature for the express purpose of privacy. I could keep looking up more apps, but that would seem to be redundant.)

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    Remote control software works differently from Windows's RDP. RDP opens a virtual session mapped to the remote host, and the screen is stick at login. Remote control software streams screen (output of VGA card) remotely and allows dual control from remote virtual mouse and local physical mouse. Passers-by can't see the screen but their random input works
    – usr-local-ΕΨΗΕΛΩΝ
    Commented Apr 12, 2021 at 11:38
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    @whatsisname it's not an explanation of why. It is a statement of fact. I'm not trying to convince anyone that it should be there. community.teamviewer.com/English/kb/articles/…
    – schroeder ♦
    Commented Apr 12, 2021 at 22:50
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    @whatsisname The feature allows a technician to protect secrets from being viewed by someone else. Anecdotally, I have an example. I used to work for an ISP. A subscriber called in because their Internet was not working. Did a trace route, found the troublesome router. I called T2 support, which transferred me to a tech. They remoted into my computer; I watched as they telnetted to the server in question, which echoed the username/password. I now had the domain name, username, and password for a router which I could have crippled. A screen blackout feature would have reduced this risk.
    – phyrfox
    Commented Apr 12, 2021 at 22:52
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    @whatsisname, ...remember, in corporate environments, the person who's remoting into a system often has more authority over what software a system runs than the person on whose desk it sits. Doubly so in call centers, retail environments, &c. where many staff members have very little authority at all. A call center tool can often have logs or other features that the call-center worker isn't authorized to see, much less use.
    – Charles Duffy
    Commented Apr 12, 2021 at 23:03
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    @whatsisname it is a statement of fact. If the OP is still skeptical, then the OP can explain the reasons for the skepticism, and we can adjust the answer. But employing a rhetorically-complete answer is inefficient until we understand the basis for the skepticism.
    – schroeder ♦
    Commented Apr 13, 2021 at 7:43
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Another legitimate use that hasn't been mentioned is for kiosk installations.

At a previous job we operated a fair few unattended kioks and would remote into them for maintenance. Showing a blank screen to random members of the public was much better than letting them see us drag around windows, run scripts or commands on the terminal or whatever else we were doing.

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    I have seen street LED billboards also configured via remote desktop
    – user11153
    Commented Apr 14, 2021 at 10:42
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One primary non-scam feature is to allow a technician to remote in to a desktop and use authentication that should not be viewed by the user. I actually worked for an ISP where a tech actually telnetted into a Cisco router that was misbehaving via my computer remotely, and they didn't blank the screen.

Back then, you could have seen the domain name, username, and password. Had I wanted to, I could have captured this information and used it to cripple large portions of the Internet, and it would be virtually untraceable back to me, and the technician who leaked their credentials would have taken the fall.

The same goes for remote workers. In some versions and types of Remote Desktop, the desktop is visible locally. This means that anyone casually sitting at your computer might see you type in usernames, passwords, credit card numbers, and any other PII that you might wish to have hidden from the general public.

Like many tools we use in real life (knives, guns, lock picks, etc), black screens have intended and unintended uses. Black screens protect data leaks and hacks for sensitive systems, and should definitely be used if you're remoting into a remote device and need to protect some data from casual observation.

It's unclear that there's a clear fix for this, because even if you add a "are you sure you wish to allow the remote user to blank your screen and scam you" prompt, people who are gullible enough to install such apps are just as likely to trust the "technician" on the other end of the line that says "Oh, don't worry about that, just click OK so I can <whatever-scam-here>".

I agree that inherently, this feature clearly will continue to be abused, but there are legitimate reasons why you'd want to have this feature available. Not having this available would lead to many more serious data leaks and havoc that hackers could use to bring down entire infrastructures.

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    I think working on a user his computer is already a big flaw in the system. Anyone could install any screen record software to remove the "black screen" feature and see what the technician was doing or not
    – Timberman
    Commented Apr 13, 2021 at 14:11
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    @Timberman Or ya know... A keylogger. You can't assume anything about the system you're logged into. Frankly, the black screen is a band aid solution, and not a real solution for real security anyway
    – Cruncher
    Commented Apr 13, 2021 at 14:34
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    @Cruncher The problem is the system in my opionion. Either use one use access tokens, or not login to the user at all. The end user's system cannot be trusted.
    – Timberman
    Commented Apr 13, 2021 at 17:48
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    @Timberman: Some systems are used primarily by users who would not have the access necessary to install such things. If the only people who would have such access are trusted by the person using the remote-access software, then screen blanking would offer meaningful security.
    – supercat
    Commented Apr 13, 2021 at 18:56
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    @Cruncher : not necessarily. You might have a workstation in your office only you can log in to. But if you need to log in remotely for any reason (you're away on a conference, or doing home office due to covid) and suddenly you need to access something from your office computer, you don't have to fear keyloggers, but you might have to fear someone casually glancing on your screen and seeing sensitive information.
    – vsz
    Commented Apr 14, 2021 at 12:40

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