Why Most ‘Secure’ AWS Setups Fail a Real Penetration Test

By the time you’re reading this, someone’s already scanned your AWS instance.

No — not a hacker in a hoodie. More likely a botnet running automated recon on public cloud footprints. And guess what? Most AWS deployments labeled “secure” by internal teams fall apart under even a half-decent pentest. Let’s break down why — without sugarcoating it.

You followed best practices… And You’re Still Vulnerable

You spun up a VPC, used IAM roles, encrypted your S3 buckets, logged into the AWS Well-Architected Tool once, and called it a day. And yet, your cloud security is still Swiss cheese. Why?

Because AWS doesn’t secure your stuff — you do. And the devil lives in the defaults, the edge cases, and the 1,000 little things you didn’t know you had to configure.

1. IAM Is a Minefield — and Everyone’s Stepping on It

IAM (Identity and Access Management) in AWS is so flexible it’s dangerous.

Most organs:

• Grant overly broad permissions to roles like EC2FullAccess because “it works.”
• Forget that service roles persist after a resource is deleted.
• Don’t audit for privilege escalation paths (a junior dev role that can attach policies? Yikes.)

In pen tests, attackers almost always find some unused or mis-scoped IAM role waiting to be exploited.

Even worse? You probably don’t have CloudTrail logs filtered in a way that tells you when it happens.

If you haven’t run PMapper or CloudSplaining against your account, you don’t know your IAM risk surface.

2. The “Default Port” Disaster

AWS doesn’t block you from shooting yourself in the foot.

• RDS databases listening on port 3306, wide open to the internet?
• Redis clusters exposed on port 6379 with no auth? Way too common.
• Is EC2 running SSH on port 22 with 0.0.0.0 access? Welcome to Botnet City.

Pen testers love scanning for default ports because people leave them open — often accidentally, sometimes due to automation scripts that override security groups.

Fix this now: Set up automated checks that flag wide-open security groups. Tools like ScoutSuite or Steampipe make this easier than you’d expect.

3. VPC Misconfigurations That No One Talks About

VPCs feel secure. They’re private! They say so in the name!

Until you realize:

• Your NAT gateway allows traffic back in via reverse TCP.
• You forgot to route logs out of the VPC, so no alerting works in real-time.
• That peered VPC with staging? It’s connected to prod.

And if you’re running Kubernetes on EKS and didn’t explicitly lock down your VPC ingress/egress? You’re inviting lateral movement.

Hard truth: Most teams have no idea how their VPC flow logs work — or where they’re stored.

4. Security Groups Are Your First Line — and They’re Weak as Hell

Here’s a brutal fact: in 9 out of 10 pen tests, security groups are misconfigured.

Common issues:

• Too many allow rules (ALLOW ALL for internal IPs? Hello, lateral movement.
• No egress restrictions, so malware can call home freely.
• No use of NACLs (network ACLs) at all — because who wants to deal with that?

Use a “deny by default” mindset, even in cloud-native environments. If that means writing more Terraform modules, so be it.

5. Logging Without Monitoring Is Just Noise

Let’s say you did enable CloudTrail, VPC Flow Logs, GuardDuty, and all the usual suspects. Great!

Now let me ask:

• Are those logs shipping to an SIEM?
• Does anyone read them?
• Can you detect a brute force attempt in the last 72 hours?

Chances are you’ve got more telemetry than you know what to do with — and no playbook to respond when something goes wrong.

We’ve seen breaches where the logs clearly showed attacker behavior… that went unnoticed for months.

6. Secrets in EC2, S3, and Code — Oh My

Secrets management is everyone’s Achilles heel.

Even if you’re using AWS Secrets Manager or Parameter Store:

• Have you disabled secrets in user-data scripts?
• Checked that old AMIs don’t have hardcoded creds.
• Made sure your Lambda environment variables aren’t leaking things?

Public S3 buckets might not leak data — but they can leak config. Think exposed .env files, debug logs, or metadata with juicy internal info.

Finally, AWS gives you powerful tools — but assumes you know how to use them securely. Security in AWS isn’t just about ticking boxes. It’s about continuous posture management, adversarial thinking, and knowing what the platform won’t do for you.