ID | Technique | Tactic |
---|---|---|
T1046 | Network Service Discovery | Discovery |
Detection: Internal Horizontal Port Scan
Description
This analytic identifies instances where an internal host has attempted to communicate with 250 or more destination IP addresses using the same port and protocol. Horizontal port scans from internal hosts can indicate reconnaissance or scanning activities, potentially signaling malicious intent or misconfiguration. By monitoring network traffic logs, this detection helps detect and respond to such behavior promptly, enhancing network security and preventing potential threats.
Search
1
2| tstats `security_content_summariesonly` values(All_Traffic.action) as action values(All_Traffic.src_category) as src_category values(All_Traffic.dest_zone) as dest_zone values(All_Traffic.src_zone) as src_zone count from datamodel=Network_Traffic where All_Traffic.src_ip IN ("10.0.0.0/8","172.16.0.0/12","192.168.0.0/16") by All_Traffic.src_ip All_Traffic.dest_port All_Traffic.dest_ip span=1s _time All_Traffic.transport
3| `drop_dm_object_name("All_Traffic")`
4| eval gtime=_time
5| bin span=1h gtime
6| stats min(_time) as _time values(action) as action dc(dest_ip) as totalDestIPCount values(src_category) as src_category values(dest_zone) as dest_zone values(src_zone) as src_zone by src_ip dest_port gtime transport
7| where totalDestIPCount>=250
8| eval dest_port=transport + "/" + dest_port
9| stats min(_time) as _time values(action) as action sum(totalDestIPCount) as totalDestIPCount values(src_category) as src_category values(dest_port) as dest_ports values(dest_zone) as dest_zone values(src_zone) as src_zone by src_ip gtime
10| fields - gtime
11| `internal_horizontal_port_scan_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
AWS CloudWatchLogs VPCflow | AWS | 'aws:cloudwatchlogs:vpcflow' |
'aws_cloudwatchlogs_vpcflow' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_summariesonly | summariesonly= summariesonly_config allow_old_summaries= oldsummaries_config fillnull_value= fillnull_config`` |
internal_horizontal_port_scan_filter | search * |
internal_horizontal_port_scan_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
To properly run this search, Splunk needs to ingest data from networking telemetry sources such as firewalls, NetFlow, or host-based networking events. Ensure that the Network_Traffic data model is populated to enable this search effectively.
Known False Positives
Unknown
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
$src_ip$ has scanned for ports $dest_ports$ across $totalDestIPCount$ destination IPs | 64 | 80 | 80 |
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | aws:cloudwatchlogs:vpcflow |
aws:cloudwatchlogs:vpcflow |
Integration | ✅ Passing | Dataset | aws:cloudwatchlogs:vpcflow |
aws:cloudwatchlogs:vpcflow |
Replay any dataset to Splunk Enterprise by using our replay.py
tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 2