Cloud Security Fundamentals: A Beginner's Guide

Welcome to Cloud Security

If you're moving to the cloud or just starting to think about security, this guide is for you. No jargon overload, no assumptions about what you already know. Just the fundamentals that matter.

The Shared Responsibility Model

This is the most important concept in cloud security. Miss this, and everything else falls apart.

The cloud provider secures: The physical infrastructure, hardware, networking equipment, and the virtualization layer.

You secure: Your data, applications, user access, network configuration, and operating systems.

Think of it like renting an apartment: The landlord maintains the building and fire safety. You're responsible for locking your door and who has your keys.

Identity: The Foundation of Everything

In the cloud, identity is your first line of defense. If someone has the right credentials, the cloud thinks they're legitimate.

Key Concepts

• Authentication: Proving who you are
• Authorization: What you're allowed to do
• Principle of Least Privilege: Give users only what they need

Practical Steps

1. Enable MFA everywhere - especially for admin accounts
2. Don't use root/owner accounts daily - create individual admin accounts
3. Use groups, not individual permissions - easier to manage
4. Review access regularly - people change roles, leave the company

Network Security Basics

Virtual Networks

Your cloud resources live in virtual networks (VPC in AWS, VNet in Azure). Think of it as your own private section of the cloud.

Put public-facing resources in public subnets. Keep databases and internal services in private subnets.

Security Groups / Firewalls

These control what traffic can reach your resources.

Default stance: Deny everything, then allow only what's needed.

Common Mistakes

• Opening SSH/RDP to the entire internet
• Putting databases in public subnets
• Overly permissive security groups

Data Protection

Encryption at Rest

Data sitting in storage should be encrypted. Most cloud services offer this by default.

Encryption in Transit

Data moving across networks should be encrypted: HTTPS, TLS for databases, encrypted VPNs.

Backup Strategy

The 3-2-1 rule: 3 copies, 2 different storage types, 1 offsite.

Logging and Monitoring

You can't protect what you can't see.

What to Log

• Authentication events
• Authorization changes
• Data access
• Configuration changes

Basic Alerts

• Root/admin account usage
• Multiple failed login attempts
• Security group changes
• Access from unusual locations

Getting Started Checklist

Week 1:

• Enable MFA on all admin accounts
• Review who has access
• Enable security dashboards

Week 2:

• Audit security groups
• Verify encryption is enabled
• Enable logging

Week 3:

• Set up basic alerts
• Document current configuration
• Identify sensitive data

Week 4:

• Review and tighten IAM permissions
• Plan regular security reviews

Keep Learning

Cloud security is a journey, not a destination. Start with the fundamentals, build good habits, and expand from there.