AWS Bedrock Guardrail Updated via UpdateGuardrail API

Alerts on CloudTrail-reported Amazon Bedrock guardrail updates, which may signal attempts to weaken safety controls.

FreeReviewedSigma · Medium · v5

Product: aws
Service: cloudtrail
Author: Marco Pedrinazzi (@pedrinazziM) (InTheCyber) (SigmaHQ), DRL 1.1
Published: 2026-07-10
Updated: 2026-07-31

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags CloudTrail events where the Bedrock service reports an UpdateGuardrail action. Updating guardrails can be used to weaken or alter safety constraints, potentially enabling unsafe or unauthorized model outputs. It relies on AWS CloudTrail telemetry for the eventName and eventSource fields corresponding to Bedrock guardrail updates.

Reporting behind it

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AWS Bedrock Guardrail Updated via UpdateGuardrail API

Pivot detection · T1685 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
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.

aws-bedrock-guardrail-updated-updateguardrail-api-via-cloudtrail-1c722651

title: AWS Bedrock Guardrail Updated via UpdateGuardrail API
id: 0e648035-0ef6-4d02-8b82-470f58681428
status: experimental
description: This rule flags CloudTrail events where the Bedrock service reports an UpdateGuardrail action. Updating guardrails can be used to weaken or alter safety constraints, potentially enabling unsafe or unauthorized model outputs. It relies on AWS CloudTrail telemetry for the eventName and eventSource fields corresponding to Bedrock guardrail updates.
references:
  - https://docs.aws.amazon.com/bedrock/latest/APIReference/API_UpdateGuardrail.html
  - https://github.com/SigmaHQ/sigma/blob/master/rules/cloud/aws/cloudtrail/aws_cloudtrail_bedrock_guardrail_updated.yml
author: Marco Pedrinazzi (@pedrinazziM) (InTheCyber), Huntrule Team
date: 2026-07-10
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  product: aws
  service: cloudtrail
detection:
  selection:
    eventName: UpdateGuardrail
    eventSource: bedrock.amazonaws.com
  condition: selection
falsepositives:
  - Legitimate guardrail updates by authorized identities.
level: medium
license: DRL-1.1
related:
  - id: 1c722651-254a-4b04-a9f4-99b62a2d0a1f
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

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