Amazon_VPC_21

Ensure 'Auto accept shared attachments' is disabled, to avoid unknown cross account attachments to your Transit Gateway

Description

Ensure you are always under the control of your environment. Always review cross-account attachment requests to your Transit gateway and approve them only if you trust the source.

Remediation

Perform the following steps in order to set ‘Auto accept shared attachments’ to disable:
1. Sign in to the Amazon VPC console at https://console.aws.amazon.com/vpc/ .
2. Choose Transit Gateways.
3. Choose relevant gateway and click Actions -> Modify.
4. Uncheck ‘Auto-accept shared attachments’.

Via CLI:
aws ec2 modify-transit-gateway –transit-gateway-id <Transit gateway ID> –options AutoAcceptSharedAttachments=disable

From TF:

resource aws_ec2_transit_gateway” “primary_gateway” {
– auto_accept_shared_attachments = “enable”
+ auto_accept_shared_attachments = “disable”
}

References :
https://docs.aws.amazon.com/vpc/latest/tgw/tgw-peering.html
CLI: https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/modify-transit-gateway.html

Service

VPC

Severity

Medium

Compliance

Mapping

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