Detection: Ollama Excessive API Requests

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: 2025-10-05 ID: 1cfab663-9adc-4169-a88c-6bae29ba3c70 Author: Rod Soto Type: Anomaly Product: Splunk Enterprise Security

Description

Detects potential Distributed Denial of Service (DDoS) attacks or rate limit abuse against Ollama API endpoints by identifying excessive request volumes from individual client IP addresses. This detection monitors GIN-formatted Ollama server logs to identify clients generating abnormally high request rates within short time windows, which may indicate automated attacks, botnet activity, or resource exhaustion attempts targeting local AI model infrastructure.

Search

 1`ollama_server` 
 2| rex field=_raw "\
 3|\s+(?<client_ip>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\s+\
 4|" 
 5| eval src=coalesce(src, client_ip) 
 6| eval dest=coalesce(dest, url, uripath, endpoint) 
 7| bin _time span=5m 
 8| stats count as request_count by _time, src, dest, host 
 9| where request_count > 120 
10| eval severity="high" 
11| eval attack_type="Rate Limit Abuse / DDoS" 
12| stats count by _time, host, src, dest, request_count, severity, attack_type 
13| `ollama_excessive_api_requests_filter`

Data Source

Name	Platform	Sourcetype	Source
Ollama Server	N/A	`'ollama:server'`	`'server.log'`

Macros Used

Name	Value
ollama_server	`(sourcetype="ollama:server")`
ollama_excessive_api_requests_filter	`search *`

ollama_excessive_api_requests_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
T1498	Network Denial of Service	Impact

Actions on Objectives

DE.AE

CIS 10

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 Risk Event	True

This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

Ingest Ollama logs via Splunk TA-ollama add-on by configuring file monitoring inputs pointed to your Ollama server log directories (sourcetype: ollama:server), or enable HTTP Event Collector (HEC) for real-time API telemetry and prompt analytics (sourcetypes: ollama:api, ollama:prompts). CIM compatibility using the Web datamodel for standardized security detections.

Known False Positives

Legitimate automated services (CI/CD pipelines, monitoring tools, batch jobs), multiple users behind NAT/proxy infrastructure, or authorized load testing activities may trigger this detection during normal operations. Operator must adjust threshold accordingly.

Associated Analytic Story

Suspicious Ollama Activities

Risk Based Analytics (RBA)

Risk Message:

Possible DDoS attack from $src$ against Ollama server detected with request count $request_count$ in 1 minute, potentially causing service degradation or complete unavailability.

Risk Object	Risk Object Type	Risk Score	Threat Objects
src	system	10	No Threat Objects

References

https://github.com/rosplk/ta-ollama

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	Not Applicable	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`server.log`	`ollama:server`
Integration	✅ Passing	Dataset	`server.log`	`ollama:server`

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: 1