New Network ACL Entry Added — Sigma Rule

Rule metadata and linked tags

Author: jamesc-grafana. Source status: test; severity: low. Source dates: 2024-07-11 / not supplied.

{
  "product": "aws",
  "service": "cloudtrail"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a3c463725ba9d81e216f6612a3dfcd8ea885f406a0c9904dad8540a5ffe87a69

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: New Network ACL Entry Added
id: e1f7febb-7b94-4234-b5c6-00fb8500f5dd
status: test
description: |
    Detects that network ACL entries have been added to a route table which could indicate that new attack vectors have been opened up in the AWS account.
references:
    - https://www.gorillastack.com/blog/real-time-events/important-aws-cloudtrail-security-events-tracking/
author: jamesc-grafana
date: 2024-07-11
tags:
    - attack.defense-impairment
    - attack.t1686.001
logsource:
    product: aws
    service: cloudtrail
detection:
    selection:
        eventSource: 'ec2.amazonaws.com'
        eventName: 'CreateNetworkAclEntry'
    condition: selection
falsepositives:
    - Legitimate use of ACLs to enable customer and staff access from the public internet into a public VPC
level: low

Original YAML and metadata in JSON

False positives

• Legitimate use of ACLs to enable customer and staff access from the public internet into a public VPC

Source references

• https://www.gorillastack.com/blog/real-time-events/important-aws-cloudtrail-security-events-tracking/