How to Audit AWS IAM Policies for Wildcard Vulnerabilities (2026 Security Guide)

The asterisk (*) is the most dangerous character in cloud computing.

When a developer is blocked by a “Permission Denied” error at 2 AM, the temptation to just add "Action": "" or "Resource": "" is overwhelming. It fixes the immediate problem. The deployment succeeds. The ticket is closed.

But that single asterisk has just planted a dormant time bomb in your AWS account. You haven’t just granted access to “that one bucket”; you might have accidentally granted permission to delete every bucket, or worse, pass administrative roles to untrusted EC2 instances.

In this guide, we are going to move beyond the generic “follow least privilege” advice. We will dig into the specific, high-risk IAM actions you need to audit right now, how to spot privilege escalation paths, and how to visualize these invisible threats before an attacker does.

1. Why Wildcards Are Worse Than You Think

Most developers understand that "Action": "s3:*" is bad. It allows deleting data. But the nuance of AWS permissions means that wildcards often grant powers you didn’t even know existed.

The “Future-Proofing” Trap

When you use a wildcard, you grant permission for all current API actions and any future actions AWS adds.

For example, if you granted dynamodb:* in 2018, you intended to allow reading/writing tables. But when AWS later released DynamoDB Streams or PartiQL, that policy automatically granted access to those new features without you reviewing them. You are effectively pre-approving permissions for services that don’t exist yet.

2. The “Toxic Combinations” to Audit

Searching for * isn’t enough. You need to look for specific combinations of permissions that attackers use for Privilege Escalation.

A. The iam:PassRole Escalation

This is the classic AWS hack. If a user has ec2:RunInstances and iam:PassRole, they can launch a new EC2 instance and assign it an existing “Admin” role. They then log into that instance and—surprise—they are now Admins.

Audit Check: Search your policies for:

{ "Effect": "Allow", "Action": [ "iam:PassRole", "ec2:RunInstances" ], "Resource": "*" }

If you see Resource: * next to iam:PassRole, you have a critical vulnerability. The resource must always be restricted to a specific, low-privilege ARN.

B. The glue:UpdateDevEndpoint Backdoor

AWS Glue is often overlooked. But if a user has glue:UpdateDevEndpoint, they can modify an existing development endpoint to use a new SSH key. This gives them shell access to the Glue environment, which often has broad VPC access.

3. How to Audit Your Policies (Manual vs. Visual)

You have hundreds of policies. How do you find the needle in the haystack?

Method 1: The “Grep” Method (Manual)

If you love the terminal, you can pull all your policies and search them textually. This is tedious but effective for a snapshot.

# Get all policy versions (Simplified logic) aws iam list-policies --scope Local --query 'Policies[*].Arn' |

xargs -I {} aws iam get-policy-version --policy-arn {} --version-id v1

The problem: JSON is hard to read. A policy might look safe because the Statement array is split into ten different blocks, hiding the dangerous combination.

Method 2: The Visual Method (Recommended)

Humans process graphs faster than JSON. Instead of reading code, you should verify permissions visually.

A good visualizer will parse the Policy JSON and explode the wildcards, showing you exactly what is effectively allowed.

4. Step-by-Step Remediation Guide

Once you find a wildcard, how do you remove it without breaking the application?

Step 1: Enable CloudTrail Logging

Before you remove a permission, you must know if it’s being used. Go to CloudTrail and search for the specific event name. If you see AccessDenied after removing a wildcard, you broke something.

Step 2: Use “Access Advisor”

In the AWS Console, the IAM User/Role tab has a section called Access Advisor. It shows you which services the user actually accessed in the last 90 days. If a user has s3:* but Access Advisor says they haven’t touched S3 in 30 days, you can safely remove the permission entirely.

Step 3: Replace Wildcards with Prefixes

You don’t always need to list every single file. Use prefixes to scope access without being overly specific.

• Bad: "Resource": "arn:aws:s3:::my-bucket/*"
• Better: "Resource": "arn:aws:s3:::my-bucket/users/${aws:username}/*"

This allows the user to do whatever they want, but only in their own folder.

5. Advanced: Conditional Keys

The strongest IAM policies don’t just limit Actions; they limit Conditions.

Even if you must grant AdministratorAccess to a developer, you can attach a condition that says “Only if MFA is enabled” or “Only from the corporate VPN IP.”

"Condition": { "IpAddress": { "aws:SourceIp": "203.0.113.0/24" } }

Frequently Asked Questions

Conclusion: Visibility is Security

AWS IAM is complex by design. It gives you granular control, but that granularity creates complexity. The asterisk is a shortcut through that complexity, but it is a shortcut that leads to data breaches.

Don’t trust your eyes to parse 500 lines of JSON. Use visualization tools, check CloudTrail logs, and aggressively prune permissions that haven’t been used in 90 days. Your future self (and your legal team) will thank you.