He tried a different approach. He didn't need to overwrite the system file; he just needed to run the portable "repack" version from an external drive, bypassing the installed software entirely. He mounted the cracked version on a USB stick and plugged it into the controller.
"Repacked" software from unofficial sources is a common vector for malware, including: chemstation software crack repack
He copied the cracked DLL. He pasted it over the secure one. The computer asked for administrator permission. He didn't have the password. He tried a different approach