Files with derp extension can be also found as files that had been renamed by DERP ransomware (October 209).
There is one other file type using
the DERP file extension!
.derp - DERP script
DERP file extension - Derp ransomware renamed file
What is derp file? How to open derp files?
File type specification:
File extension derp can be also encountered on files that were encrypted and renamed by DERP ransomware that appeared sometime around October 2019.
When this ransomware affects your computer, it renames all encrypted files and adds .derp suffix on top of existing file extension. A _readme.txt is also created in affected folders and contains instructions.
It looks like there is currently (October 2019) no tool available, that could reliably decrypt .derp files, but usually some appear later.