Yeah, that's why I hate shoes. Because people who commit crimes normally wear them.
OP: rar is very very common for anything made by a Linux computer.
If you're on Linux, you make .tar.gz or .tar.bz2 or something. Or .zip, I guess you see sometimes. But RAR? That's a windows people thing, in my experience.
As sibling commenters said, you're probably thinking of .tar. Now that I run into a lot. :-)
I probably installed it many years ago from the repositories. Now that linux gaming is so good I've been seeing 7z and rar being used for game mods a lot.