VPC with private subnets has no S3 endpoint

Severity: Low
Service: S3
Check ID: S3_NO_VPC_ENDPOINT

What this check finds

A VPC with private subnets reaches Amazon S3 over the public internet (via NAT/IGW) rather than a private S3 gateway endpoint. A gateway endpoint keeps S3 traffic on the AWS network, is free, and lets endpoint policies restrict which buckets are reachable — reducing the data-exfiltration path.

Passing looks like: Private S3 access via VPC gateway endpoint.

How to fix it

Create an S3 gateway endpoint and associate it with the VPC's private route tables.

AWS console

VPC → Endpoints → Create endpoint → AWS services → com.amazonaws.{region}.s3 (Gateway) → select the VPC and private route tables.

Compliance controls it is evidence for

A failing result counts against these controls in KloudLytics; a passing one is evidence towards them. How compliance mapping works

Compliance controls mapped to VPC with private subnets has no S3 endpoint
Framework	Controls
NIST SP 800-53 Rev5 (Moderate)	CA-3 Information Exchange SC-7 Boundary Protection
NIST Cybersecurity Framework 2.0	PR.IR-01 Networks and environments are protected from unauthorized logical access and usage
ISO/IEC 27001:2022 Annex A	A.8.20 Networks security A.8.21 Security of network services

Checked on every scan

KloudLytics runs this check each time it scans a connected AWS account, through a read-only role, and lists every affected resource with its region. On Pro and Business a fix is written for the specific resource rather than the general case above. The exact access it needs

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