AWS EC2 Network Access Control List Creation

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Identifies the creation of an AWS Elastic Compute Cloud (EC2) network access control list (ACL) or an entry in a network ACL with a specified rule number.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-aws*

Severity: low

Risk score: 21

Runs every: 10 minutes

Searches indices from: now-60m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Cloud
  • AWS
  • Continuous Monitoring
  • SecOps
  • Network Security

Version: 9 (version history)

Added (Elastic Stack release): 7.9.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Network ACL’s may be created by a network administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment. Network ACL creations by unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.

Investigation guide

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Rule query

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event.dataset:aws.cloudtrail and event.provider:ec2.amazonaws.com and
event.action:(CreateNetworkAcl or CreateNetworkAclEntry) and
event.outcome:success

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 9 (8.4.0 release)
  • Formatting only
Version 7 (8.1.0 release)
  • Formatting only
Version 6 (7.13.0 release)
  • Updated query, changed from:

    event.action:(CreateNetworkAcl or CreateNetworkAclEntry) and
    event.dataset:aws.cloudtrail and event.provider:ec2.amazonaws.com and
    event.outcome:success
Version 5 (7.12.0 release)
  • Formatting only
Version 4 (7.11.2 release)
  • Formatting only
Version 3 (7.11.0 release)
  • Formatting only
Version 2 (7.10.0 release)
  • Formatting only