Bedrock Inference Profile and Cross-Region Inference with Control Tower Restrictions

When using Amazon Bedrock with inference profiles in an AWS environment restricted by Control Tower, you may encounter challenges accessing required regions.

This article explains how to maintain security while enabling necessary cross-region access for Bedrock.

The Challenge

Amazon Bedrock inference profiles require permissions in us-west-2, but your Control Tower configuration blocks services outside your allowed regions (us-east-1 and us-east-2).

**Recommended Solutions

Option 1: Modify Service Control Policies (SCPs) to Allow Cross-Region Inference

Create an exception in your region deny SCP using one of these approaches:

Using Condition with ArnNotLike:

{

"Version": "2012-10-17",

"Statement": [

{

  "Sid": "DenySpecificRegionAllowCRI",

  "Effect": "Deny",

  "Action": "*",

  "Resource": "*",

  "Condition": {

    "StringEquals": {

      "aws:RequestedRegion": "us-west-2"

    },

    "ArnNotLike": {

      "bedrock:InferenceProfileArn": "arn:aws:bedrock:*:*:inference-profile/*"

    }

  }

}

]

}

Using NotAction approach:

{

"Version": "2012-10-17",

"Statement": [

{

  "Effect": "Deny",

  "NotAction": "bedrock:*",

  "Resource": "*",

  "Condition": {

    "StringEquals": {

      "aws:RequestedRegion": [

        "us-west-2"

      ]

    }

  }

}

]

}

These policies create specific exceptions for Bedrock within your regional restrictions.

Option 2: Use Control Tower's Exemption Parameters

If using Control Tower Region deny controls (MULTISERVICE.PV.1), modify the configuration to exempt specific Bedrock actions using the ExemptedActions

parameter:

ExemptedActions: ["bedrock:InvokeModel*"]

Implementation Plan for SCP Strategy

1. Assessment of Current Controls

The AWS-GR_REGION_DENY guardrail restricts access to services outside your governed regions without exceptions, preventing Bedrock usage in us-west-2.

2. Verification of CT.MULTI.SERVICE.PV.1 Capabilities

CT.MULTI.SERVICE.PV.1 supports the granularity needed with configurable parameters:

• AllowedRegions: Specifies which regions are allowed

• ExemptedActions: Specifies actions exempt from region restrictions

• ExemptedPrincipalARNs: Specifies principals exempt from restrictions

3. Implementation Steps

Step 1: Disable the AWS-GR_REGION_DENY Guardrail

• Log into the AWS Control Tower console

• Navigate to Controls Library

• Search for AWS-GR_REGION_DENY

• Disable the control

Step 2: Enable CT.MULTI.SERVICE.PV.1 Control for All OUs

• Navigate to Controls Library

• Search for CT.MULTI.SERVICE.PV.1

• Enable the control

• For each OU, configure AllowedRegions: us-east-1,us-east-2

Step 3: Create Bedrock Exemption for Specific OU

• Select the OU requiring Bedrock access

• Configure parameters:

o AllowedRegions: us-east-1,us-east-2

o ExemptedActions: bedrock:InvokeModel*,bedrock:GetFoundationModel

4. Validation Steps

After implementation:

• Verify standard OUs can only access services in us-east-1 and us-east-2

• Verify Bedrock-enabled OUs can access regular services in us-east-1/us-east-2 and Bedrock in us-west-2

• Verify users cannot access other services in us-west-2

5. Best Practices

• Implement least privilege principles

• Set up monitoring for cross-region traffic

• Regularly review exemptions as Bedrock expands to more regions

• Check model availability across regions

• Document exceptions for audit purposes

• Schedule periodic reviews

• Consider complementary IAM policies for finer control

By following this approach, you can maintain your security posture while enabling the specific cross-region access needed for Bedrock inference profiles.