Im not sure if mine was?
My hard drive was failing and i needed to back things up and using the internet at the time was a pain because of loading flash ads and such so i searched google for a stop flash app for safari.
not having used any safari extensions before i wasn't sure where to look or them so used google.
Having downloaded one i installed it, but could not find it anywhere on my system, not in safari and no spotlight search, applications or utilities.
i then proceeded to download another which did work as expected.
Two days later my gmail was hacked and used for sending of spam messages.
now this could just be a coincidence but ive since had a hard drive replacement i carnt check but its a good idea to remember there may be some things out there that the more advanced users will not touch/use and others will simply use/open and as such give away access to things.