It has been a couple of years since I tested this issue. Defender and Lavasoft were the two that I had tested so if their encryption techniques have changed, I would be unaware of it. Since that time, I have not re-tested them, because leaving the box unchecked (Avasts default setting) eliminated the problems I was having with false positives. I easily dismissed them as such since on the four machines I had been working on, other anti-malware scanners could not find anything.
If you suspect that your machine is compromised, at a very minimum, run the real time "Standard Shield" set to high. If doubt still remains after double checking with alternative scanners, test it again on another computer or (if you have the time) after doing a clean reformat.
All this depends on how seriously you are convinced (or worried).