Many users search for "UPD" (Update) because they already own Sierra. Apple allows you to re-download previously purchased macOS versions.
But one night, Leo noticed something. He’d been ripping a DVD for a relative. When the encoding finished, Finder didn’t just move the file. A window popped up—terminal-style text crawling across the screen. Download Mac Os Sierra 10.12 6 Dmg UPD
SierraElevatedHelper never reappeared.