Nchsk19zip 2021 Upd -

: Trojan horses hidden within the archive or the downloader.

. It may refer to a specific internal file name, a niche local competition (potentially a school-level "National Cyber" or "National Chemistry" event), or a private archive from 2021. nchsk19zip 2021

Because this is not a recognized historical or pop-culture event, its "story" would likely be specific to the person or group who created it. Common possibilities for such a file name include: : Trojan horses hidden within the archive or the downloader