CGMANI-7825 avatar image
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CGMANI-7825 asked LimitlessTechnology-2700 published

How is that Google Chrome can make itself the default PDF viewer?

Ok, first of all I DON'T WANT suggestions on how to change my default applications, I'm a very seasoned system administrator and I'm well aware of how to do it.

Since Windows 10 ONLY allows me as a sys admin to set a list of default application associations via an .xml file ONE TIME at a computer login or a user login via GPO, HOW IN THE WORLD DOES GOOGLE CHROME REPEATEDLY KEEP CHANGING THE DEFAULT PDF VIEWER TO ITSELF FOR MY USERS????

I've been working on this for months now and it is really piss poor that Microsoft does not let sys admins control the default file associations to the degree they are doing it now. That would be FAR MORE SECURE than MS deciding that their stupid piss poor browser is the best options if a registry key that controls it is changed. These types of controls might be fine for stupid home users, but not for business. If MS can't successfully allow for optimal functionality between both then perhaps they need to have two lines of products one for business where sys admins are allowed to do their jobs and one for stupid home users.

I just had another user with this issue today. They logged on to their computer, my GPO did its job set the default pdf viewer to Adobe Reader, the user opened/closed several pdf files no problem. A short time later goes to open a pdf file and it opens in CHROME!!!

I scrubbed through the registry on the computer and NOWHERE was there an association between chrome and pdf files, in fact it was quite the opposite every pdf file association and userchoice key was set to Adobe as it should be. However in settings, apps, default apps, view apps by file types it listed chrome and all shortcuts to pdfs had a chrome icon and opened in chrome.

So obviously there is a serious FLAW in Microcraps plan to protect and keep a users default application file associations. So if anyone out there knows how chrome is doing this, when I can't even get around it as a sys admin, or can help fix the root cause of this issue, I would greatly appreciate it.

Thanks in advance!

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1 Answer

LimitlessTechnology-2700 avatar image
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LimitlessTechnology-2700 answered LimitlessTechnology-2700 published

Hello @CGMANI-7825,

I understand all right. In my case took some months (it was an educational entity, with hundreds of PCs) but I hope this can serve as some example:

What the team found was a legacy GPO was used to set either Adobe Read or Adobe Pro as the default PDF reader for the user based on security groups using the next registry key: HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts.pdf\UserChoice\Progid. A new Hash value in Windows 10 is also added to UserChoice key.

In a repro we found that either having no ProdID or a randomized ProdID, then opening a PDF with Chrome, Chrome would then be the default PDF application. Basically your file association ProdID MUST match the Adobe version hash. If not it will revert.

Setting the file association to Adobe would then create the correct Hash value, then when accessing a PDF with Chrome, it would reload the default. Then we disabled the GP applying the registry change, and have changed to using the Win10 supported method using Set a default associations configuration file GP for our users.

We did also try with some policy with WMI filtering and as far I remember there was some success in some deployments. I don't have exactly recorded the change documentation, but the related classes:

Application Name: Adobe Acrobat 2017
ProgID: Acrobat.Document.2017
WMI Filter: select from cim_datafile where (Name = "C:\\Program Files (x86)\\Adobe\\Acrobat 2017\\Acrobat\\Acrobat.exe" or Name = "C:\\Program )

Application Name: Adobe Acrobat Reader DC
ProgID: AcroExch.Document.DC
WMI Filter: select * from cim_datafile where (Name = "C:\\Program Files (x86)\\Adobe\\Acrobat Reader DC\\Reader\\AcroRd32.exe" or Name = "C:\\Program Files\\Adobe\\Acrobat Reader DC\\Reader\\AcroRd32.exe")

Application Name: Adobe Acrobat DC
ProgID: Acrobat.Document.DC
WMI Filter: select * from cim_datafile where (Name = "C:\\Program Files\\Acrobat\\acrobat.exe" or Name = "C:\\Program Files (x86)\\Acrobat\\acrobat.exe")

Application Name: Adobe Acrobat X
ProgID: AcroExch.Document
WMI Filter: select * from cim_datafile where (Name = "c:\\Program Files\\Adobe\\Acrobat 10.0\\Acrobat\\Acrobat.exe" or Name = "c:\\Program Files (x86)\\Adobe\\Acrobat 10.0\\Acrobat\\Acrobat.exe")

Application Name: Adobe Acrobat XI
ProgID: Acrobat.Document.11
WMI Filter: select * from cim_datafile where (Name = "C:\\Program Files\\Adobe\\Acrobat 11.0\\Acrobat\\Acrobat.exe" or Name = "C:\\Program Files (x86)\\Adobe\\Acrobat 11.0\\Acrobat\\Acrobat.exe")

Hope this helps with your issue,

--If the reply is helpful, please Upvote and Accept as answer--

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