>The report also contains a pretty useless firewall rule named "PAS TOOL PHP WEB KIT FOUND" that can be used to search malware in PHP files. It is interesting that they have replaced digits in 'base64_decode' function name with regexp as if there were any other similar functions.

If you read that regexp carefully, it's more complicated than that. It doesn't match base64_decode, but it would match `='base'.(32*2).'_de'.'code'`. That's obfuscation in the payload, and in another comment I linked to some code that uses exactly this unusual (and pointless) obfuscation [1]

[1] https://news.ycombinator.com/item?id=13281008