is there a way to copy creation/modified date to exif tag of images via exiftool?

[beb]

Exiftool is not a standalone utility. At the first launch, she unpacks her perl distribution into the Temp folder for 20+ seconds, leaving all this garbage there...

This actually appears to be the case. Didn't know this. Thanks.

Determine the exact format in CMD:
exiftool -s test.jpg|find/i "date"

Just in case, there's also a native option for that:
exiftool test.jpg -time:all
or, as I prefer to use it,
exiftool test.jpg -directory -filename -G1 -a -time:all