We are running the latest patched versions of the following
- Windows 10 1809 OS Build 17763.914
- Office 2016 Professional Plus 32 Bit 16.0.4266.1001
- Adobe Acrobat Reader DC Version 2019.021.20058
The problem affects all documents that Windows decides have come from untrusted sources- eg files from Internet, email and even network drives. These files can be identified in file properties as below.
When a user tries to open an untrusted pdf, docx or xlsx files, Protected View should engage with standard office and acrobat security settings in place.
the user will experience a 5-10 minute delay in opening these documents, the application will freeze and will not open any document for this duration
We have managed to put a workaround in place disabling the Acrobat Secure app container using this reg key Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Adobe\Acrobat Reader\DC\FeatureLockDown\"bEnableProtectedModeAppContainer" = 0 (default is 1) and also by disabling the Protected View Features in Office as necessary to keep some users working but this is a significant compromise to our security profile and we need to revert those changes asap.
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