Nginx Core Dump — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2021-05-31 / 2023-05-08.

{
  "service": "nginx"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: b3a03dbed72f5005d04dfc56e92a0504d4644c620982b44f886d53b8c741579d

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Nginx Core Dump
id: 59ec40bb-322e-40ab-808d-84fa690d7e56
status: test
description: Detects a core dump of a crashing Nginx worker process, which could be a signal of a serious problem or exploitation attempts.
references:
    - https://docs.nginx.com/nginx/admin-guide/monitoring/debugging/#enabling-core-dumps
    - https://www.x41-dsec.de/lab/advisories/x41-2021-002-nginx-resolver-copy/
author: Florian Roth (Nextron Systems)
date: 2021-05-31
modified: 2023-05-08
tags:
    - attack.impact
    - attack.t1499.004
logsource:
    service: nginx
detection:
    keywords:
        - 'exited on signal 6 (core dumped)'
    condition: keywords
falsepositives:
    - Serious issues with a configuration or plugin
level: high

Original YAML and metadata in JSON

False positives

• Serious issues with a configuration or plugin

Source references

• https://docs.nginx.com/nginx/admin-guide/monitoring/debugging/#enabling-core-dumps
• https://www.x41-dsec.de/lab/advisories/x41-2021-002-nginx-resolver-copy/