Newly Observed High Severity Suricata Alert

[metadata]
creation_date = "2026/01/20"
integration = ["suricata"]
maturity = "production"
updated_date = "2026/02/17"

[rule]
author = ["Elastic"]
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 prioritize triage and response.
"""
from = "now-7205m"
interval = "5m"
language = "esql"
license = "Elastic License v2"
name = "Newly Observed High Severity Suricata Alert"
risk_score = 99
rule_id = "d591d7af-399b-4888-b705-ae612690c48d"
severity = "critical"
tags = ["Use Case: Threat Detection", "Rule Type: Higher-Order Rule", "Resources: Investigation Guide", "Domain: Network", "Data Source: Suricata"]
timestamp_override = "event.ingested"
type = "esql"

query = '''
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
'''
note = """## 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."""
references = ["https://www.elastic.co/docs/reference/integrations/suricata"]