This KQL query grabs defined RMM domains within the RMML project and matches them against MDE telemetry.
See also the original blog post here.
// Define the regex constructor function which transforms an array of patterns into regex.
let regexConstructor = (arr:dynamic) { replace_string( replace_string(replace_string( replace_string(strcat('((?i)', strcat_array( arr,'|') ,')'), '.','[.]'), @'\',@'\\'), @'/',@'\/'), @'*', @'.*') };
// ----------------------------------------------------------------
// Download the JSON string and convert to a usable object.
let RMMs = externaldata(RMMs:string)[h@'https://github.com/LivingInSyn/RMML/releases/download/v1.4.0/rmms.json'] with(format='raw');