While often associated with specific file formats in certain contexts, in this usage, it is frequently a custom or encrypted extension used to identify files related to specific, often private, hacking frameworks or dumps [2].
on what "SLIGHTSTALKER" does.
This is likely the name of a specific hacking tool, a script for data scraping (stalking/monitoring), or a moniker for a threat actor [1, 2]. While often associated with specific file formats in