Detect DNS tunneling

Elastic Stack Beats
7

Looks like you have DNS data indexed in Packetbeat. Here's a sample query to look for some interesting domains.

curl http://<elasticsearch>:9200/packetbeat-*/dns/_search?pretty -d'
{
  "query": {
    "bool": {
      "filter": {
        "range": {
          "@timestamp": {
            "from": "now-4h"
          }
        }
      },
      "must_not": {
        "terms": {
          "dns.question.etld_plus_one": [
            "akadns.net.",
            "amazonaws.com.",
            "apple.com.",
            "apple-dns.net.",
            "cloudfront.net.",
            "icloud.com.",
            "in-addr.arpa.",
            "google.com.",
            "yahoo.com."
          ]
        }
      }
    }
  },
  "size": 0,
  "aggs": {
    "by_domain": {
      "terms": {
        "size": 0,
        "field": "dns.question.etld_plus_one"
      },
      "aggs": {
        "unique_hostnames": {
          "cardinality": {
            "field": "dns.question.name"
          }
        },
        "total_bytes_in": {
          "sum": {
            "field": "bytes_in"
          }
        },
        "total_bytes_out": {
          "sum": {
            "field": "bytes_out"
          }
        },
        "high_num_hostnames": {
          "bucket_selector": {
            "buckets_path": {
              "unique_hostnames": "unique_hostnames"
            },
            "script": "unique_hostnames > 10"
          }
        }
      }
    }
  }
}'