Sigma rule: Ingress/Egress Security Group Modification

Rule

Title

Ingress/Egress Security Group Modification

Status

test

Level

medium

Author

jamesc-grafana

Date

2024-07-11

File

rules/cloud/aws/cloudtrail/aws_cloudtrail_security_group_change_ingress_egress.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

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.

Log source

product

aws

service

cloudtrail

Detection

selection:
    eventSource: 'ec2.amazonaws.com'
    eventName:
        - 'AuthorizeSecurityGroupEgress'
        - 'AuthorizeSecurityGroupIngress'
        - 'RevokeSecurityGroupEgress'
        - 'RevokeSecurityGroupIngress'
condition: selection

False positives (as the rule lists them)

• 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

Tags

• attack.initial-access
• attack.t1190

MITRE ATT&CK ids this rule names

• T1190

References

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/cloud/aws/cloudtrail/aws_cloudtrail_security_group_change_ingress_egress.yml