Something installed flashplayer-plugin today, and I don't know what it was.
 

Yes, I noticed that Firefox had the shockwave flashplayer plugin. I looked around and found /lib/x86-64/flashplugin-installer had a couple of files in it including a script called install_plugin and a .so file. These had creation dates of today, October 5. Now, I do not remember installing flashplugin, because I don't want it. I am wondering how it got installed and how I can keep it from installing automatically again? This is not cool.

there was a SECURITY update to "fix" another security hole in flash

expect 1 to 2 PER WEEK
flash is very insecure and 1 to 3 new holes are found almost every week

as to installing flash

the default firefox rpm/deb will AUTO install flash
you did not have to do anything to have it installed

Unless you're running as root, I don't see how anything could install automatically.
At some point you would have needed to either furnish your root password or, in the case of sudo, your user password.

Thanks that explains it.