AWS IAM Least-Privilege Audit: Eliminating Wildcard Permissions

Introduction

Wildcard permissions ("*") in AWS IAM policies violate the principle of least privilege, creating unnecessary security risks. This guide demonstrates how to identify and remediate over-permissive policies using AWS-native tools.

Why Wildcards Are Dangerous

1. Over-Privileged Access: Grants unintended permissions across entire AWS services
2. Attack Surface Expansion: Increases risk of credential compromise abuse
3. Compliance Violations: Fails standards like CIS AWS Foundations Benchmark

Identification Methods

# Example dangerous policy
{
  "Effect": "Allow",
  "Action": ["s3:*"],
  "Resource": "*"
}

Automated Detection Tools:

• AWS Access Analyzer: Scans for externally shared wildcards
• IAM Policy Simulator: Tests permissions against specific actions
• AWS Config Rules: iam-policy-no-statements-with-admin-access

Remediation Steps

1. Action-Level Granularity:

# Least-privilege alternative
{
  "Effect": "Allow",
  "Action": [
    "s3:GetObject",
    "s3:PutObject"
  ],
  "Resource": "arn:aws:s3:::specific-bucket/*"
}

2. Resource Constraints:

   • Replace "Resource": "*" with explicit ARNs
   • Implement condition keys (e.g., aws:RequestedRegion)

3. Access Advisor Utilization:

   • Review last-accessed timestamps in IAM Console
   • Remove unused permissions

Continuous Monitoring

• Enable IAM Access Analyzer for policy validation
• Implement permission boundaries for human users
• Schedule quarterly policy reviews with AWS Config

Advanced Techniques

• SCP Chaining: Combine service control policies with IAM
• AWS Backup Vault Lock: Prevent wildcard deletion rights
• Cross-Account Conditionals: Restrict sts:AssumeRole with aws:PrincipalAccount

Official AWS Documentation Reference