For those using Windows OSs (including server versions) I would recommend Dr.Web CureIT! utility as a standalone scanning anti-virus / anti-rootkit utility or Dr.Web LiveDisk containing the same Dr.Web CureIt! utility and a couple of other useful tools for sysadmins in case if a Windows OS machine cannot boot.
These tools are totally free for non-profit / personal use and they come from an old Russian antivirus lab owned by Mr. Igor Danilov.
We all are more familiar with the Russian Kapsersky-brand due to a massive marketing effort set forth by brothers Kaspersky lab.
But Kaspersky lab appeared a bit later and after Mr. Danilov's lab.
All additional info can be found here:
https://free.drweb.com/download+cureit+free/?lng=en and here:
https://free.drweb.com/aid_admin/?lng=en.
I hope this info will be useful to many people over here.