Thanks for your feedback. Yes, I am talking about /Users/Shared/. No, I don't consider it a long term solution. It is just something I came up with a way to "stick a finger in a hole in the dike" as it were, until a proper solution could be found. I think I've already run into a couple of quirky things happening with new installations. Do you have any ideas about how I can rid my system of this? I would be most grateful for any solution you can offer.
I'm having this same problem with a sudden appearance of Safariextinstall. I'd like to know if there's a solution out there. I noticed that it's activity is based around an executable file appearing in the Shared user account which then leads to other things happening culminating in the attempt to install an extension in Safari. The temporary solution I've come up with is to make the Shared user account read only, but I'd love to know if there is a permanent solution out there to remove it once and for all. Thanks,