As an aside, for those looking to understand YARA rules, [1] provides a brief introduction and [2] introduces how to write them. I needed to look it up myself, but seems relatively straightforward if you have a programming background. tl;dr: YARA rules are a method of categorizing malware based on their characteristics. So the PDF here released a YARA rule to determine a specific piece of malware used in the hack (it…
And they replaced digits in 'base64_decode' with regexp as if there were other similar functions.