Avast alerted me that there was a rootkit running in the backround today and prompted me to delete it and do a bootscan, which I did.
Bootscan came back clean, as did a scan with both MBAM and SAS. However, since I hear these things can be sneaky, I followed the guide here and did a scan with OTL and aswMBR to be sure. It looks like something is still there…but I’m not sure since I am, obviously, not the expert.