using pkgchk -l -p /usr/bin/kstat command shows you the package which contains kstat file. Package name isSUNWesu
Pathname: /usr/bin/kstat
Type: regular file
Expected mode: 0555
Expected owner: root
Expected group: bin
Expected file size (bytes): 5410
Expected sum(1) of contents: 10440
Expected last modification: Jan 06 01:56:20 2000
Referenced by the following packages:
SUNWesu
Current status: installed