A vast YARA repository covering many different types of attack

https://github.com/Yara-Rules/rules

"A YARA rules repository continuously updated for monitoring the old and new threats from articles, incidents response"

https://github.com/StrangerealIntel/Orion

A curated list of awesome YARA rules, tools, and resources.

https://github.com/InQuest/awesome-yara

Florian Roth's YARA rule set.

https://github.com/Neo23x0/signature-base/tree/master/yara

and godmode YARA rule

https://gist.github.com/Neo23x0/f1bb645a4f715cb499150c5a14d82b44

YARA debugger

https://yaradbg.dev/