I've been having an issue recently where something has been randomly and silently erasing the contents of /etc/hosts on some of the Macs I support. If I modified the file and added the proper entries, the file would be zero bytes again shortly thereafter. I noted that this zeroing out corresponded exactly with the creation of hosts.efi.bak, which I doubt is a coincidence.

I just uninstalled and reinstalled the software on one of the affected Macs, and we'll see if this fixes the issue (so far so good).