Detection: Internal Vulnerability Scan

EXPERIMENTAL DETECTION

This detection status is set to experimental. The Splunk Threat Research team has not yet fully tested, simulated, or built comprehensive datasets for this detection. As such, this analytic is not officially supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2026-02-25 ID: 46f946ed-1c78-4e96-9906-c7a4be15e39b Author: Dean Luxton Type: TTP Product: Splunk Enterprise Security

Description

This analytic detects internal hosts triggering multiple IDS signatures, which may include either more than 25 signatures against a single host or a single signature across over 25 destination IP addresses. Such patterns can indicate active vulnerability scanning activities within the network. By monitoring IDS logs, this detection helps identify and respond to potential vulnerability scanning attempts, enhancing the network's security posture and preventing potential exploits.

Search

 1
 2| tstats `security_content_summariesonly` values(IDS_Attacks.action) as action values(IDS_Attacks.src_category) as src_category values(IDS_Attacks.dest_category) as dest_category count FROM datamodel=Intrusion_Detection.IDS_Attacks
 3  WHERE IDS_Attacks.src IN (10.0.0.0/8,192.168.0.0/16,172.16.0.0/12) IDS_Attacks.severity IN (critical, high, medium)
 4  BY IDS_Attacks.src IDS_Attacks.severity IDS_Attacks.signature
 5     IDS_Attacks.dest IDS_Attacks.dest_port IDS_Attacks.transport
 6     span=1s _time
 7
 8| `drop_dm_object_name("IDS_Attacks")`
 9
10| eval gtime=_time
11
12| bin span=1h gtime
13
14| eventstats count as sevCount
15  BY severity src
16
17| eventstats count as sigCount
18  BY signature src
19
20| eval severity=severity +"("+sevCount+")"
21
22| eval signature=signature +"("+sigCount+")"
23
24| eval dest_port=transport + "/" + dest_port
25
26| stats min(_time) as _time values(action) as action dc(dest) as destCount dc(signature) as sigCount values(signature) values(src_category) as src_category values(dest_category) as dest_category values(severity) as severity values(dest_port) as dest_ports
27  BY src gtime
28
29| fields - gtime
30
31| where destCount>25 OR sigCount>25
32
33| `internal_vulnerability_scan_filter`

Data Source

No data sources specified for this detection.

Macros Used

Name	Value
security_content_summariesonly	`summariesonly=`summariesonly_config `allow_old_summaries=`oldsummaries_config `fillnull_value=`fillnull_config``
internal_vulnerability_scan_filter	`search *`

internal_vulnerability_scan_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1595.002	Vulnerability Scanning	Reconnaissance
T1046	Network Service Discovery	Discovery

Exploitation

Reconnaissance

DE.CM

CIS 13

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

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

For this detection to function effectively, it is essential to ingest IDS/IPS logs that are mapped to the Common Information Model (CIM). These logs provide the necessary security-related telemetry and contextual information needed to accurately identify and analyze potential threats.

Known False Positives

Internal vulnerability scanners will trigger this detection.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Large volume of IDS signatures triggered by $src$

Risk Object	Risk Object Type	Risk Score	Threat Objects
src	system	64	No Threat Objects

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	Not Applicable	N/A	N/A	N/A
Unit	❌ Failing	N/A	`N/A`	`N/A`
Integration	❌ Failing	N/A	`N/A`	`N/A`

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: 6