huntrule

AWS CloudTrail ELB/ALB Security Group Changes via ApplySecurityGroupsToLoadBalancer or SetSecurityGroups

Alerts on CloudTrail events that change ELB/ALB security groups by applying or setting load balancer security groups.

FreeReviewedSigma · Medium · v5
Product
aws
Service
cloudtrail
Author
jamesc-grafana (SigmaHQ), DRL 1.1
Published
2024-07-11
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Initial Access

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags CloudTrail events where an Elastic Load Balancer (ELB) or Application Load Balancer (ALB) has its attached security groups modified using ApplySecurityGroupsToLoadBalancer or SetSecurityGroups. Changing load balancer security groups can expand or alter inbound network access, which may reflect misconfiguration or an attacker adjusting connectivity into VPC/subnet resources. Detection relies on CloudTrail telemetry with eventSource elasticloadbalancing.amazonaws.com and the specific eventName values.

Reporting behind it

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AWS CloudTrail ELB/ALB Security Group Changes via ApplySecurityGroupsToLoadBalancer or SetSecurityGroups
Pivot detection · T1190 · 9 related

Changelog

v5
  1. v5
    Candidate ingested via manual entry.2026-07-31
  2. v4
    Candidate ingested via manual entry.2026-07-31
  3. v3
    Candidate ingested via manual entry.2026-07-31
  4. v2
    Candidate ingested via manual entry.2026-07-31
  5. v1
    No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.