Ingress/Egress Security Group Modification — Sigma Rule

Rule metadata and linked tags

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

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: c23b903deb40fefbb02eb93410d5b6ee6c656beb09d11d14ef500692b60f0b40

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: Ingress/Egress Security Group Modification
id: 6fb77778-040f-4015-9440-572aa9b6b580
status: test
description: |
    Detects when an account makes changes to the ingress or egress rules of a security group.
    This can indicate that an attacker is attempting to open up new attack vectors in the account, that they are trying to exfiltrate data over the network, or that they are trying to allow machines in that VPC/Subnet to contact a C&C server.
references:
    - https://www.gorillastack.com/blog/real-time-events/important-aws-cloudtrail-security-events-tracking/
author: jamesc-grafana
date: 2024-07-11
tags:
    - attack.initial-access
    - attack.t1190
logsource:
    product: aws
    service: cloudtrail
detection:
    selection:
        eventSource: 'ec2.amazonaws.com'
        eventName:
            - 'AuthorizeSecurityGroupEgress'
            - 'AuthorizeSecurityGroupIngress'
            - 'RevokeSecurityGroupEgress'
            - 'RevokeSecurityGroupIngress'
    condition: selection
falsepositives:
    - New VPCs and Subnets being setup requiring a different security profile to those already defined
    - A single port being opened for a new service that is known to be deploying
    - Administrators closing unused ports to reduce the attack surface
level: medium

Original YAML and metadata in JSON

False positives

• New VPCs and Subnets being setup requiring a different security profile to those already defined
• A single port being opened for a new service that is known to be deploying
• Administrators closing unused ports to reduce the attack surface

Source references

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