What are the best practices for securing EC2 instances?

Difficulty: 5/10

IAM roles, Network security, Instance hardening

EC2 Security Hardening

Securing EC2 involves a multi-layered approach focusing on identity, networking, and software updates. Following the principle of least privilege ensures that instances only have the permissions and network access absolutely necessary for their function.

Top Security Practices

1
Use IAM Roles instead of long-term access keys.
2
Apply the principle of least privilege to Security Group rules (avoid 0.0.0.0/0).
3
Regularly patch the OS and applications using AWS Systems Manager Patch Manager.
4
Disable password-based SSH logins and use SSH keys or Session Manager.
5
Enable VPC Flow Logs to monitor network traffic for anomalies.

Scenario Questions

0-2 years experience

1How would you configure SSH access to a new EC2 instance to follow security best practices?
2If an instance is reachable from the internet on port 22, what immediate steps would you take to remediate it?
3What IAM role settings would you apply to ensure the instance only has the permissions it truly needs?

Follow-up Questions

Can you elaborate on how you'd rotate SSH keys at scale?
What metrics or logs would you monitor to detect a compromised instance?
How would you expose a needed public endpoint while keeping the instance otherwise private?