Virus

[FlerysGaMe2032]

This didn't happen before

[FlerysGaMe2032]

[FlerysGaMe2032]

[FlerysGaMe2032]

[FlerysGaMe2032]

[FlerysGaMe2032]

[FlerysGaMe2032]

[FlerysGaMe2032]

I dont know but possible this without viruses. You also can check this

mmc-cracked-win32.zip

[NeXProgger]

In short: microsoft recently started another crackdown on cracked Minecraft.

If you downloaded the launcher from github, then there is almost no reason to worry.
I checked UltimMC's source code and uploaded binaries on Virustotal around a year ago, it was all clean. As there were no changes to code in this repo for 2 years, the builds can be considered safe.