Ask HN: Are Adobe Acrobat updates a security hole?

tl; dr: It seems like it'd be easy to spoof a "software update" dialog, and thereby install arbitrary malicious code. The reason I ask: Very often, a dialog appears that says something like, "There is a security update to Adobe Acrobat...Do you want to install?" And if I say yes, the next dialog prompts me for my password (I'm on a Mac, FWIW.) and if I give it the password, it moves forward and installs the new software. (The frequency of the updates also seems suspicious; I understand that pdfs are a prime vector for malware, though I don't understand why.) Anyway, my main question is: How do I know that this is legit? Since I always have a browser open, it seems credible that someone could craft a pop-up window to mimic the Adobe Updater dialog. (I have a pop-up blocker, but imagine that it would be possible to get past that.) Am I right to be concerned about this? And if so, what to do? Forgive me if this is I naive question; I'm no expert about security matters.