net_dns_high_subdomain_rate.yml

title: High DNS subdomain requests rate per domain
id: 8198e9a8-e38f-4ba5-8f16-882b1c0f880e
description: High rate of unique Fully Qualified Domain Names (FQDN) requests per root domain (eTLD+1) in short period of time
author: Daniil Yugoslavskiy, oscd.community
date: 2019/10/21
modified: 2019/11/04
tags:
    - attack.exfiltration
    - attack.t1048
logsource:
    category: dns
detection:
    dns_question_name:
        query: "*"
    default_list_of_well_known_domains:
        query_etld_plus_one: 
            - "akadns.net"
            - "akamaiedge.net"
            - "amazonaws.com"
            - "apple.com"
            - "apple-dns.net"
            - "cloudfront.net"
            - "icloud.com"
            - "in-addr.arpa"
            - "google.com"
            - "yahoo.com"
            - "dropbox.com"
            - "windowsupdate.com"
            - "microsoftonline.com"
            - "s-microsoft.com"
            - "office365.com"
            - "linkedin.com"
    timeframe: 15m
    condition: count(subdomain) per query_etld_plus_one per computer_name > 200 and not default_list_of_well_known_domains
    #    for each host in timeframe
    #                for each dns_question_etld_plus_one
    #                    if number of dns_question_name > 200
    #                        dns_question_etld_plus_one is not in default_list_of_well_known_domains
falsepositives:
    - Legitimate domain name requested, which should be added to whitelist
level: high
status: unsupported