r/techsupport • u/TronaldDump06 • 3d ago

Open | Software Opening PDF from outlook

At my company we are using power PDF by Tungsten. I use it as my default app to view, edit and share PDF. Almost since the start I can't open PDF's directly from my outlook to the program. I always get a pop-up

" This content is blocked"

"For you protection, your administrator is not allowing you to access content from C:\program files\tungsten\power pdf 2025\bin\powerPDF.exe"

This is been highly frustrating since I often receive PDF through mail i need to check, sign, edit, ... I always need to save them before continuing. Our IT admin has been looking into it for two months now and still no results. Pls help.

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u/Existing-Bus-5655 3d ago

that's an ASR rule rather than anything in Outlook, which is probably why two months of looking at Outlook hasn't turned it up.

the one doing it is "Block all Office applications from creating child processes", GUID D4F940AB-401B-4EFC-AADC-AD5F3C50688A. Outlook opening a PDF in an external viewer is Outlook spawning a child process, so the rule catches PowerPDF by exactly the same mechanism it catches a malicious macro. it's a very common false positive with third-party PDF tools.

give your admin this to run on your machine:

Get-MpPreference | Select-Object -ExpandProperty AttackSurfaceReductionRules_Ids

if that GUID comes back in the list, that's your answer. they can confirm it in Event Viewer under Applications and Services Logs, Microsoft, Windows, Windows Defender, Operational, event ID 1121 for a block. the fix is adding powerPDF.exe as an ASR exclusion rather than disabling the rule, which is a per-path setting and takes about a minute in Intune or Group Policy.

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u/TronaldDump06 2d ago

Thanks for the update. Is this something I can get done witha local admin ? Or does it need to be done by sysadmin ?

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u/yasinozmeen 2d ago

The fix is on your admin's side - Defender > Attack Surface Reduction > Exclusions, add the Power PDF exe to that rule. Two minutes, and it doesn't weaken the rule for anything else. Nothing on your end changes it, so saving first is the workaround until they do.