Windows Detect Network Scanner Behavior

name: Windows Detect Network Scanner Behavior
id: 78e678d2-bf64-4fe6-aa52-2f7b11dddee7
version: 9
creation_date: '2024-12-26'
modification_date: '2026-05-13'
author: Steven Dick
status: production
type: Anomaly
description: The following analytic detects when an application is used to connect a large number of unique ports/targets within a short time frame. Network enumeration may be used by adversaries as a method of discovery, lateral movement, or remote execution. This analytic may require significant tuning depending on the organization and applications being actively used, highly recommended to pre-populate the filter macro prior to activation.
data_source:
    - Sysmon EventID 3
search: '| tstats `security_content_summariesonly` count values(All_Traffic.action) as action values(All_Traffic.dest) as dest values(All_Traffic.dest_port) as dest_port values(All_Traffic.dest_ip) as dest_ip values(All_Traffic.dvc) as dvc values(All_Traffic.direction) as direction values(All_Traffic.protocol) as protocol values(All_Traffic.protocol_version) as protocol_version values(All_Traffic.src_port) as src_port values(All_Traffic.transport) as transport dc(All_Traffic.dest_port) as port_count dc(All_Traffic.dest) as dest_count min(_time) as firstTime max(_time) as lastTime values(All_Traffic.process_id) as process_id from datamodel=Network_Traffic.All_Traffic where sourcetype=XmlWinEventLog All_Traffic.app = "*\\*" All_Traffic.dest_port < 32000 NOT All_Traffic.dest_port IN (8443,8080,5353,3268,443,389,88,80,53,25) by All_Traffic.app All_Traffic.src All_Traffic.src_ip All_Traffic.user All_Traffic.vendor_product _time span=5m | `drop_dm_object_name(All_Traffic)` | rex field=app ".*\\\(?<process_name>.*)$" | where port_count > 10 OR dest_count > 10 | stats latest(src) as src, latest(src_ip) as src_ip, max(dest_count) as dest_count, max(port_count) as port_count, latest(dest_port) as dest_port, min(firstTime) as firstTime, max(lastTime) as lastTime, max(count) as count by user,app,process_name | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_detect_network_scanner_behavior_filter`'
how_to_implement: This detection relies on Sysmon EventID 3 events being ingested AND tagged into the Network_Traffic datamodel.
known_false_positives: Various, could be noisy depending on processes in the organization and sysmon configuration used. Adjusted port/dest count thresholds as needed.
references:
    - https://attack.mitre.org/techniques/T1595
intermediate_findings:
    entities:
        - field: src
          type: system
          score: 20
          message: A process exhibiting network scanning behavior [$process_name$] was detected on $src$
        - field: user
          type: user
          score: 20
          message: A process exhibiting network scanning behavior [$process_name$] was detected on $src$
threat_objects:
    - field: process_name
      type: process_name
analytic_story:
    - Network Discovery
    - Windows Discovery Techniques
asset_type: Endpoint
mitre_attack_id:
    - T1595.001
    - T1595.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: network