﻿---
title: Newly Observed High Severity Suricata Alert
description: This rule detects Suricata high severity alerts that are observed for the first time in the previous 5 days of alert history. Analysts can use this to...
url: https://www.elastic.co/elastic/docs-builder/docs/2824/reference/security/prebuilt-rules/rules/cross-platform/newly_observed_suricata_alert
products:
  - Elastic Security
---

# Newly Observed High Severity Suricata Alert
This rule detects Suricata high severity alerts that are observed for the first time in the previous 5 days of alert history.
Analysts can use this to prioritize triage and response.
**Rule type**: esql
**Rule indices**:
**Rule Severity**: critical
**Risk Score**: 99
**Runs every**: 5m
**Searches indices from**: `now-7205m`
**Maximum alerts per execution**: 100
**References**:
- [[https://www.elastic.co/docs/reference/integrations/suricata](https://www.elastic.co/docs/reference/integrations/suricata)](https://www.elastic.co/docs/reference/integrations/suricata)

**Tags**:
- Use Case: Threat Detection
- Rule Type: Higher-Order Rule
- Resources: Investigation Guide
- Domain: Network
- Data Source: Suricata

**Version**: 2
**Rule authors**:
- Elastic

**Rule license**: Elastic License v2

## Investigation guide


## Triage and analysis


### Investigating Newly Observed High Severity Suricata Alert

This rule surfaces newly observed, low-frequency high severity suricata alerts within the last 5 days.
Because the alert has not been seen previously for this rule and host, it should be prioritized for validation to determine
whether it represents a true compromise or rare benign activity.

### Investigation Steps

- Identify the source address, affected host and review the associated rule name to understand the behavior that triggered the alert.
- Validate the source address under which the activity occurred and assess whether it aligns with normal behavior.
- Refer to the specific alert details like event.original to get more context.


### False Positive Considerations

- Vulnerability scanners and pentesting.
- Administrative scripts or automation tools can trigger detections when first introduced.
- Development or testing environments may produce one-off behaviors that resemble malicious techniques.


### Response and Remediation

- If the activity is confirmed malicious, isolate the affected host to prevent further execution or lateral movement.
- Terminate malicious processes and remove any dropped files or persistence mechanisms.
- Collect forensic artifacts to understand initial access and execution flow.
- Patch or remediate any vulnerabilities or misconfigurations that enabled the behavior.
- If benign, document the finding and consider tuning or exception handling to reduce future noise.
- Continue monitoring the host and environment for recurrence of the behavior or related alerts.


## Rule Query

```esql
FROM logs-suricata.*

  // high severity alerts
| where event.module == "suricata" and event.kind == "signal" and event.severity == 1 and
        rule.name is not null and
        not rule.name like "SURICATA STREAM*"

| STATS Esql.alerts_count = count(*),
        Esql.first_time_seen = MIN(@timestamp),
        Esql.distinct_count_src_ip = COUNT_DISTINCT(source.ip),
        Esql.distinct_count_dst_ip = COUNT_DISTINCT(destination.ip),
        src_ip_values = VALUES(source.ip),
        dst_ip_values = VALUES(destination.ip),
        url_dom = VALUES(url.domain),
        url_path = VALUES(url.path) by rule.name, event.type

| eval Esql.recent = DATE_DIFF("minute", Esql.first_time_seen, now())
  // first time seen is within 10m of the rule execution time
| where Esql.recent <= 10 and
// exclude high volume alerts such as vuln-scanners
  Esql.alerts_count <= 5 and Esql.distinct_count_src_ip <= 2 and Esql.distinct_count_dst_ip <= 2

// move dynamic fields to ECS quivalent for rule exceptions
| eval source.ip = MV_FIRST(src_ip_values),
       destination.ip = MV_FIRST(dst_ip_values),
       url.domain = MV_FIRST(url_dom),
       url.path = MV_FIRST(url_path)
| keep rule.name, event.type, Esql.*, source.ip, destination.ip, url.domain, url.path
```