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I have an employee who reads books in PDF form while he should be working. When he senses I'm coming around he just closes the file. I can't really take drastic action against him (i.e. firing him) because he fills a role that will be hard to replace. I've tried to uninstall all the different versions of PDF readers he finds but there are just too many of them. Is there a way to just prevent Windows from opening files with the extension .PDF?

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Is his PC part of a domain where group policies can be used? Are you legally allowed to block this (no private use allowed in general)? – nixda Nov 23 '13 at 20:03
If he's filling the role (doing the job he was hired to do), then why do you care? Have you removed his admin access? – Ƭᴇcʜιᴇ007 Nov 23 '13 at 20:37
You need to speak with him if it's interfering with his work. Because even most browsers can open PDFs without you having anything local installed. – nerdwaller Nov 23 '13 at 21:35
"Its my machine and he's on my time. " You have to be very careful thinking like this. If there are no formal policies stating this that he has signed that he understands this, or if you are in a state that is very much workers rights... Especially if he is fulfilling his job role! You can't very well fire him for reading when he is meeting his responsibilities. If he isn't then you really should let him go regardless of his unique role, there is someone else that can do it. Unless his role is circumventing your attempts to block PDFs. – AthomSfere Nov 23 '13 at 22:29
(trying to write some sort of real solution). There are a lot of pdf readers so blocking some of them won't work. They can be read from most browsers nowadays. I could see at least two possibilities for the first case but I've never implemented them: preventing Explorer from accessing the file through the Registry and preventing access at file-system (NTFS) level. However I also have to agree on what has been said: if your worker is doing his job, maybe reading those books might increase his productivity. If he isn't, explain why he shouldn't read in work time and try to reach a consensus. – Doktoro Reichard Nov 24 '13 at 1:30
up vote 12 down vote accepted

If your employee has some minimal knowledge of computers, he can work around any protection that you can put in place.

The strongest protection I can think of is to regedit to :


Then delete all sub-keys entries whose name starts with OpenWithList and finish by destroying the permissions on these keys so that no viewer of PDF can re-register itself. This will only block a double-click on a .pdf file.

However, this won't stop the guy from starting his PDF viewer and using the Open menu.

You can then use a similar suggestion to that of Rik's comment and setup his antivirus to block all PDF files. He will then upload all his PDF files to Google Docs and use their viewer, or use Dropbox or any other of the numerous other on-line services.

You will then use the corporate/router's firewall to disallow these very numerous services, and the guy will just use a free VPN service to bypass that one.

You will next block these (again very numerous) VPN services, and the guy will convert his .pdf files to .doc and keep on reading.

And are you really sure that he does not need ever to look at a PDF file when doing his job?

Conclusion: You cannot win - for every measure there is a counter-measure. Your only gain will be to start a war with a valuable employee who just might have enough and leave your company.

I really suggest that you have a quiet and open talk with the guy and try to arrive at an agreement.

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I think that this answer is really the best. It's much like people trying to stop piracy - You can't. If someone wants to do something they will find a way to do it. – Frank Nov 26 '13 at 21:09
I really like it. Provided a good explanation on why this is not a good idea, but actually answered the question. – NothingsImpossible Dec 1 '13 at 1:46
I did forget about the fact anyone nowadays has .pdf readers inbedded inside their e-mail providers, Dropbox and the likes, without the need to actually download the files, even though I use them everyday. Anyway, was kind of disappointed with the quality of the answers this question lead to but, as @chipperyman573 stated, it is like stopping piracy. Your answer gets the bounty for being the only suggesting and explaining a concrete solution (and explaining why this is a near pointless endeavor). – Doktoro Reichard Dec 3 '13 at 18:05

Maybe just maybe one of these programms help to achieve your goal.

Just stumbling up this question and it made me curious, therefore these links. I did not test them!
Normally I should not link to external programms (at least I think it is not wishfull) but here you go:

a small tool to lock files (not 100% sure if it also prevent opening a file)
This one can protect your private files and folders.

Both for Windows only. Good luck.

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I've seen both links. Although I haven't tested them, they only lock specific files; as such, anyone with access to the original files could just open them elsewhere. – Doktoro Reichard Dec 3 '13 at 18:00

Yes, and your employee will follow up by using a different format altogether or even simply changing the extension to '.notapdf'. Can you prevent him from opening a paper book he brings to work? Use your stern voice and tell the slacker to do something productive.

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Although this is a solution... it is not a technical solution. As Superuser isn't The Workplace, these kinds of solutions aren't the best fit for here, IMO. – Doktoro Reichard Nov 24 '13 at 1:20
@DoktoroReichard: I agree a non-technical answer is a bad fit for the site, but I maintain a technical answer would be a bad fit for the question. – Marcks Thomas Nov 24 '13 at 1:31
The OP didn't state a lot about the work environment, so all we are doing is supposing if the worker is actually doing his job and in the process the reading of books is excusable. Besides, Superuser is a place for computer related problems, not workplace ones. Anyone that actually tries to search about this topic, but with different motives, will get a bunch of answers and comments that do nothing to solve the problem stated, which is to prevent at all costs the opening of a .pdf file. – Doktoro Reichard Nov 24 '13 at 1:35

If he has no admin rights work with a white-list of programs that he can use. Like it's done for guest accounts.

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Any details on how to set his computer like that? – gronostaj Nov 23 '13 at 23:34
Via policies or the easy way activating the "Parental Safety" of a user account. For me the second solution was the better and faster way, setting up policies took me half a day, the build-in parental safety 30minutes with the same result: only allowing a webbrowser, the explorer, office and an antivirus ;) – inselberg Nov 24 '13 at 9:15
The problem, in my opinion, would be the web browser and, as it was said, the vast unsurmountable amount of programs used to open .pdf... If you could explain how one would do what you pretend it would go a long way in creating a good answer. – Doktoro Reichard Nov 26 '13 at 15:41
The point is that a white list don't cares about the "unsurmountable amount of programs used to open .pdf.". The user isn't able to start/install/what ever you don't want him too. The browser issue can be solved by disabling the pdf extension. But and i have to admit, that's maybe the key-problem, if he don't want to work, he will find other ways. So JimDel has to fire him anyways one day, so spending time to find a new employee is (imho) a better solution. – inselberg Nov 26 '13 at 22:25
At any rate... can you develop more about your answer? – Doktoro Reichard Nov 26 '13 at 23:45

When you use Windows 7 or Windows 8 Enterprise you can use AppLocker to stop the execution of all PDF related tools.

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The answer could benefit from an explanation, even more so that AppLocker seems like a very user-unfriendly feature. – Doktoro Reichard Dec 3 '13 at 17:59

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