Be warned that malware like this is in the AUR all the time. It's so common it's not even newsworthy. They are usually pretty good at handling it though.

I've never heard of this happening and I can't find a single occurrence of it. I mean, I agree with "don't blindly trust everything in the AUR", but this seems wrong.

I maintain 14 AUR packages and have also never heard of this happening.

Also, the aur community seems to be very active.

Any sources/articles for this?

citation needed

The AUR is really handy, but you do need to be careful. Arch does not pretend to hold the user's hand, and you're not likely to get much sympathy from the community if you get bitten by recklessly installing stuff from the AUR.

Also, as far as I know, pacaur is no longer maintained. I switched to trizen, which prints the PKGBUILD on screen before allowing the user to opt in to executing it. Not going to pretend that I always review the PKGBUILD thoroughly, but I do generally skim them, applying more scrutiny as packages become more obscure.

For packages with many votes this is somewhat fine, but you should still skim the PKGBUILD as the maintainers of even popular packages may change in time.

I'd recommend checking both PKGBUILD and clicking "View Changes" to see who (and what) the last few authors have been up to.

It's relatively common for people to be added as co-maintainers after posting even just one helpful comment (!) in an unpopular package, so it's worth double-checking to make sure a big change hasn't been made recently without the author's permission.

If this is your means to secure your system you may be in for a rude awakening.