[IMGate] new virus extension ?

[Serhan Sevim]

Today, one of my users received a virus (bypassing IMGate) which is detected
by Norton Antivirus  but the extension of the virus was youlllovethis.enc
.enc is something that I've never heard of, I tried to put it into my
workstation and execute it but funnily enough it's not even recognized by
windows as an executable file. Than how come a virus could be infectious if
it is the case that it's not even executable ?
Thank you for any input.
Serhan,