Custom event category in correlation rule

Can anyone please explain what does it means

I have Symantec antimalware logs on index pattern logstash-sepm*. In json document I don't have event.category field but I want to create a correlation rule what if the same malware detects on multiple hosts. So I have to first select a value present in event.category like "process" or anything else. I want to declear field "type" as my event.catoegory but it deoesnot work.

Can anyone please explain me how can I define custom event.category here ^

EQL uses the @timestamp and event.category
Yes you can cusotmize fields when running the query using your custom code or from Kibana Dev Console, but from the Kibaba SIEM UI, there is a call to the endpoint :

POST https://localhost:5601/internal/search/eql
{
  "params": {
    "allow_no_indices": true,
    "index": "my-index",
    "body": {
      "query": ""timestamp_field": "file.accessed" xxxxxx",
      "size": 0
    }
  },
  "options": {
    "ignore": [
      400
    ]
  }
}

So you need to have @timestamp and event.category in your index
Then use only the content of the query

As far as I could understand from the documentation is, we can define custom field like "event_category_field": "file.type" as an event.category if and only if we don't have event.category in the json document.

Here I want to ask how can I define event_category_field through kibana UI. I know kibana UI objective is to run the EQL syntax only but if I am wanting to declear my custom field as event.category how will it be accomplished.

Thank you

Simply you can't from the UI

ok thank you for your reply