Perfect — let’s start by drafting the updated EC2 Hardening Guide. I’ll keep it detailed, actionable, and structured so it’s easy to follow, while also signaling authority to both readers and Google.

EC2 Hardening Guide (Updated 2025)

Last updated: September 2025. This guide consolidates AWS official best practices, CIS Benchmarks, and real-world experience to help you secure Amazon EC2 instances.

1. System Updates & Patch Management

  • Enable automatic patching with AWS Systems Manager (SSM):

    sudo yum update -y     # Amazon Linux
sudo apt-get update && sudo apt-get upgrade -y   # Ubuntu/Debian

  • Use SSM Patch Manager to automate OS/security updates across fleets:

    • Create a Patch Baseline.
    • Attach to EC2 via IAM Role with SSM managed policy.
    • Schedule via Maintenance Windows.

2. Least Privilege IAM Roles

  • Never hardcode credentials inside EC2.

  • Attach an Instance Role with only the permissions needed:

    {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": ["s3:GetObject"],
      "Resource": ["arn:aws:s3:::mybucket/*"]
    }
  ]
}

  • Enable IAM Access Analyzer to detect overly broad permissions.

3. Network Security

  • Restrict inbound traffic with Security Groups:

    • Deny 0.0.0.0/0 on SSH/RDP; instead allow only trusted IP ranges.
    • Example rule: 22/tcp → 203.0.113.0/24.

  • Add Network ACLs for an extra layer of defense.

  • Require VPN/Bastion host for administrative access.

4. OS Hardening

  • Disable root login over SSH:

    sudo nano /etc/ssh/sshd_config
PermitRootLogin no
PasswordAuthentication no

  • Enforce key-based authentication (it is preferable to only allow SSM auth)

  • Configure firewalld/ufw inside the OS for host-based filtering.

  • Remove unused software packages.

5. Disk & Data Protection

  • Encrypt EBS volumes with AWS KMS CMK.
  • Use automatic snapshot encryption for backups.
  • Enable EBS fast snapshot restore only in secure regions.
  • If handling sensitive data → enforce KMS key rotation (every 365 days).

6. Monitoring & Logging

  • Enable CloudTrail for all regions → send logs to S3 + CloudWatch Logs.

  • Use GuardDuty for continuous threat detection.

  • Enable VPC Flow Logs for visibility into network traffic.

  • Install CloudWatch Agent on EC2:

    sudo yum install amazon-cloudwatch-agent -y
/opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-config-wizard

7. Backup & Recovery

  • Use AWS Backup with lifecycle rules for snapshots.
  • Store snapshots in separate accounts (backup vaults).
  • Regularly test recovery from snapshots/AMI.

8. Compliance & Benchmarking

  • Use AWS Security Hub with CIS EC2 controls enabled.

  • Run AWS Config with rules like:

    • restricted-ssh
    • ec2-instance-managed-by-ssm
    • ec2-ebs-encryption-by-default

I’ll be posting soon a full walthrough about Meeting CIS Benchmarks for EC2.

With these steps, your EC2 instances are aligned with AWS and CIS best practices, reducing attack surface while staying auditable for compliance.