In extension is associated with Spyware - harmful file. You can try to delete these files by antivirus softwares.
IN file extension is a record file which used for tracking transactions of your computer. It is used by spy softwares. If you get an in extension file on your computer, you should better install an antivirus software.
Especially, if the file name looks like any name from the following list, you should make provision against to these files. Until then you souldnt enter any password on your computer.
Here is the name list of harmful files:
What to use in
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