Can i still get hacked through pdf attachments if i make them read-only before opening them? I am not in cybersecurity but someone told me this way i would be safer?
I would say yes, if the pdf contains malicious code that could be loaded by the reader making the pdf file read only doesn’t do anything.
Not necessarily, if the PDF is printed as multiple images.
The OP asked if making a pdf file read only would make it more secure to open. Regardless of the pdf content I don’t see how changing the file attribute could be beneficial, it just make impossible to modify the file itself.
If you’re worried about this, your best bet is probably Dangerzone. It basically opens the file in a sandbox, takes a picture of each page (which leaves you without any hidden code or malicious links), and then converts that to PDF, leaving you with a document that is pretty much guaranteed safe.