Complete Cloud Security Guide

1. Cloud Security Fundamentals

Cloud computing has transformed IT infrastructure, but it introduces new security challenges. Understanding the shared responsibility model is crucial: cloud providers secure the underlying infrastructure, while customers are responsible for securing their data, applications, and configurations.

1.1 Shared Responsibility Model

2. Identity and Access Management

2.1 IAM Best Practices

• Least Privilege: Grant minimum required permissions
• MFA Everywhere: Require MFA for all human users
• No Root Usage: Never use root/admin account for daily tasks
• Rotate Credentials: Regular key rotation; use temporary credentials
• Role-Based Access: Group permissions by job function

2.2 AWS IAM Example

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "s3:GetObject",
                "s3:PutObject"
            ],
            "Resource": "arn:aws:s3:::my-bucket/*",
            "Condition": {
                "IpAddress": {
                    "aws:SourceIp": "10.0.0.0/8"
                }
            }
        }
    ]
}

2.3 Service Accounts

For applications, use service accounts with roles instead of static keys. AWS uses IAM roles for EC2/Lambda; Azure uses Managed Identities; GCP uses Service Accounts with Workload Identity.

3. Network Security

3.1 VPC/VNet Design

• Use private subnets for databases and backend services
• Place only load balancers and bastion hosts in public subnets
• Use NAT gateways for outbound internet from private subnets
• Enable VPC Flow Logs for network visibility

3.2 Security Groups

# AWS Security Group - Web Server
Inbound:
  - TCP 443 from 0.0.0.0/0 (HTTPS)
  - TCP 22 from 10.0.0.0/8 (SSH from internal only)

Outbound:
  - TCP 443 to 0.0.0.0/0 (HTTPS)
  - TCP 3306 to sg-database (MySQL to DB security group)

# Never allow:
  - 0.0.0.0/0 to 0.0.0.0/0 (all traffic)
  - SSH (22) from 0.0.0.0/0 (use bastion)

4. Data Protection

4.1 Encryption

• At Rest: Enable encryption for all storage (S3, EBS, RDS)
• In Transit: TLS 1.2+ for all communications
• Key Management: Use cloud KMS; avoid storing keys with data
• Customer Managed Keys: Greater control for sensitive data

4.2 S3 Bucket Security

# Block public access (AWS CLI)
aws s3api put-public-access-block \
    --bucket my-bucket \
    --public-access-block-configuration \
    "BlockPublicAcls=true,IgnorePublicAcls=true,BlockPublicPolicy=true,RestrictPublicBuckets=true"

# Enable encryption
aws s3api put-bucket-encryption \
    --bucket my-bucket \
    --server-side-encryption-configuration \
    '{"Rules":[{"ApplyServerSideEncryptionByDefault":{"SSEAlgorithm":"aws:kms"}}]}'

5. Logging and Monitoring

5.1 Essential Logs

5.2 Centralized Logging

Send all logs to a centralized location (CloudWatch, Azure Monitor, Stackdriver, or SIEM). Set up alerts for suspicious activity like IAM changes, large data transfers, or access from unusual locations.

6. Compliance and Governance

• AWS: Config Rules, Control Tower, Security Hub
• Azure: Policy, Blueprints, Security Center
• GCP: Organization Policy, Security Command Center

6.1 Compliance Frameworks

Cloud providers offer compliance certifications (SOC 2, ISO 27001, HIPAA, PCI-DSS). However, certification of the infrastructure doesn't mean your workload is compliant—you must configure it correctly.

7. Cloud Security Tools

8. Frequently Asked Questions

Conclusion

Cloud security is primarily about configuration and access control. Understand the shared responsibility model, implement least-privilege IAM, encrypt everything, log extensively, and use automated security tools. Most cloud breaches are preventable with proper configuration and monitoring.

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