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AWS IAM Roles Anywhere Trust Anchor Created with External CA

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AWS IAM Roles Anywhere Trust Anchor Created with External CAedit

Identifies when an AWS IAM Roles Anywhere Trust Anchor with an external certificate authority is created. AWS Roles Anywhere profiles are legitimate profiles that can be created by administrators to allow access from any location. This rule detects when a trust anchor is created with an external certificate authority that is not managed by AWS Certificate Manager Private Certificate Authority (ACM PCA). Adversaries may accomplish this to maintain persistence in the environment.

Rule type: query

Rule indices:

  • filebeat-*
  • logs-aws.cloudtrail-*

Severity: medium

Risk score: 47

Runs every: 10m

Searches indices from: now-30m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Domain: Cloud
  • Data Source: AWS
  • Data Source: Amazon Web Services
  • Data Source: AWS IAM
  • Use Case: Identity and Access Audit
  • Tactic: Persistence

Version: 1

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guideedit

Triage and Analysis

Investigating AWS IAM Roles Anywhere Trust Anchor Created with External CA

This rule detects when an AWS IAM Roles Anywhere Trust Anchor with an external certificate authority is created. AWS Roles Anywhere profiles are legitimate profiles that can be created by administrators to allow access from any location. This rule identifies when a trust anchor is created with an external certificate authority that is not managed by AWS Certificate Manager Private Certificate Authority (ACM PCA). Adversaries may accomplish this to maintain persistence in the environment.

Possible Investigation Steps:

  • Identify the Actor: Review the aws.cloudtrail.user_identity.arn and aws.cloudtrail.user_identity.access_key_id fields to identify who made the change. Verify if this actor typically performs such actions and if they have the necessary permissions.
  • Review the Request Details: Examine the aws.cloudtrail.request_parameters to understand the specific details of the trust anchor creation. Look for any unusual parameters that could suggest unauthorized or malicious modifications.
  • Analyze the Source of the Request: Investigate the source.ip and source.geo fields to determine the geographical origin of the request. An external or unexpected location might indicate compromised credentials or unauthorized access.
  • Contextualize with Timestamp: Use the @timestamp field to check when the trust anchor was created. Changes during non-business hours or outside regular maintenance windows might require further scrutiny.
  • Correlate with Other Activities: Search for related CloudTrail events before and after this change to see if the same actor or IP address engaged in other potentially suspicious activities.
  • Verify the Certificate Authority: Ensure that the external certificate authority used is authorized and recognized. Unauthorized external CAs can be a red flag for malicious activity.

False Positive Analysis:

  • Legitimate Administrative Actions: Confirm if the trust anchor creation aligns with scheduled updates, development activities, or legitimate administrative tasks documented in change management systems.
  • Consistency Check: Compare the action against historical data of similar actions performed by the user or within the organization. If the action is consistent with past legitimate activities, it might indicate a false alarm.
  • Verify through Outcomes: Check the aws.cloudtrail.response_elements and the event.outcome to confirm if the creation was successful and intended according to policy.

Response and Remediation:

  • Immediate Review and Reversal if Necessary: If the creation was unauthorized, remove the trust anchor and revoke any associated permissions.
  • Enhance Monitoring and Alerts: Adjust monitoring systems to alert on similar actions, especially those involving the creation of trust anchors with external certificate authorities.
  • Educate and Train: Provide additional training to users with administrative rights on the importance of security best practices concerning IAM Roles Anywhere and the use of certificate authorities.
  • Audit IAM Roles and Policies: Conduct a comprehensive audit of all IAM roles and associated policies to ensure they adhere to the principle of least privilege.
  • Incident Response: If there’s an indication of malicious intent or a security breach, initiate the incident response protocol to mitigate any damage and prevent future occurrences.

Additional Information:

For further guidance on managing IAM Roles Anywhere and securing AWS environments, refer to the AWS IAM Roles Anywhere documentation and AWS best practices for security. Additionally, consult the following resources for specific details on IAM roles and trust anchors: - AWS IAM Roles Anywhere Introduction - Ermetic Blog on IAM Users and Third Parties

Rule queryedit

event.dataset: aws.cloudtrail
    and event.provider: rolesanywhere.amazonaws.com
    and event.action: CreateTrustAnchor
    and event.outcome: success
    and not aws.cloudtrail.request_parameters: *sourceType=AWS_ACM_PCA*

Framework: MITRE ATT&CKTM

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