tL;dr
Control AWS access via endpoint policies
A VPC endpoint policy allows you to control which AWS principals and actions are allowed through your private network connection to a service like S3. To enforce a VPC endpoint policy in AWS, attach a resource-based policy to the endpoint that explicitly allows or denies access to specific services, accounts, or actions. This is crucial for locking down access to AWS S3 buckets or other resources over a VPC endpoint and tightening your AWS security posture.
Sola lets you skip the mental gymnastics of stitching together IAM policies, bucket policies, and endpoint configs. Just ask the right question (like “Who can access my S3 buckets via this VPC endpoint?”) and get the answer, immediately. Use the AWS Network Security Posture app or build your own with Sola’s AI co-pilot to see how your endpoint policies are actually behaving.
Sola lets you skip the mental gymnastics of stitching together IAM policies, bucket policies, and endpoint configs. Just ask the right question (like “Who can access my S3 buckets via this VPC endpoint?”) and get the answer, immediately. Use the AWS Network Security Posture app or build your own with Sola’s AI co-pilot to see how your endpoint policies are actually behaving.
Sola apps that could help you
Visit the App GalleryUnderstand the VPC Endpoint Policy Basics
When using a VPC endpoint for S3, the first trap people fall into is assuming it’s “private, so it’s safe.” Not quite. Without a VPC endpoint policy, anyone with network access to the VPC can hit S3 (assuming their IAM role allows it). Endpoint policies give you an additional access control layer that enforces “who can use this VPC endpoint to talk to this service.”
The policy syntax is similar to standard IAM policies. You define actions, resources, and principals, but scoped to what goes through the endpoint. For example, you might allow only a specific IAM role to access a particular S3 bucket via a given endpoint, and deny everything else.
The key is: the endpoint policy only affects traffic through the endpoint, it won’t stop access over the public internet, unless your bucket policy also enforces aws:SourceVpce.
Best Practices for Enforcing Endpoint Policies
- Use explicit denies for anything you absolutely want to block. IAM allows are permissive by default.
- Combine with S3 bucket policies to restrict access based on the
aws:SourceVpcecondition key. This ensures that even if a user has access, they must go through the intended VPC endpoint. - Avoid overly broad permissions—limit access to exact actions (e.g.
s3:GetObject) and specific resources. - Test using IAM Policy Simulator or CloudTrail logs to validate that your endpoint policy behaves as expected.
- Tag your VPC endpoints and enforce tagging policies via SCPs or automation if you’re running multi-account setups.
Don’t just write it. Enforce it with Sola.
Want to know if your VPC endpoint policy is actually doing what you think it’s doing? Sola helps you find out in minutes. Use the AWS Network Security Posture app or build your own logic using Sola’s AI-powered studio. Just define your question (“Is any VPC endpoint letting in unwanted roles?”), connect your data source, and you’ve got an answer. No need for audits, spreadsheets, or assumptions—just the security truth, now.