AWS handles some parts of security, and you handle others. Knowing where the line is drawn is essential for cloud security.
1Security OF the Cloud (AWS)
AWS is responsible for protecting the infrastructure that runs all of the services offered in the AWS Cloud. This infrastructure is composed of the hardware, software, networking, and facilities that run AWS Cloud services.
2Security IN the Cloud (Customer)
Customer responsibility is determined by the AWS Cloud service that a customer selects. This determines the amount of configuration work the customer must perform as part of their security responsibilities. Customers are responsible for managing their data (including encryption), classifying their assets, and using IAM tools to apply the appropriate permissions.
3Step-by-Step Breakdown
Security and Compliance is a shared responsibility between AWS and the customer. This is known as the Shared Responsibility Model.
AWS is responsible for 'Security OF the Cloud'. This includes the physical security of data centers, hardware, software, and networking that runs AWS services.
Checkpoint: Who is responsible for the physical security of AWS data centers?
- →AWS
- →The Customer
The Customer is responsible for 'Security IN the Cloud'. This includes data encryption, OS patching, network configuration, and IAM management.
Depending on the service (IaaS, PaaS, or SaaS), the line of responsibility shifts. In IaaS (like EC2), you do more. In SaaS (like S3), AWS does more.
Checkpoint: If you launch an EC2 instance, who is responsible for patching the Guest Operating System?
- →AWS
- →The Customer
Understanding this model is crucial for passed exams and for keeping your cloud environments secure.
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Accessibility (A11y)
1Compliance Documentation Must Be Accessible to Auditors Using Assistive Technology
Security and compliance artifacts (IAM policy exports, audit trails) are often reviewed by auditors who may use screen readers — ensure internal compliance tooling exports genuinely accessible formats, not just images of tables.
2Clearly Labeled Responsibility Diagrams Help Every Reader, Not Just Sighted Ones
A visual-only diagram splitting AWS vs. customer responsibilities excludes screen reader users entirely unless it's paired with an equivalent structured text description of the same division.
SEO Implications
- 1
Misunderstanding This Model Is a Leading Cause of Real-World Data Breaches
Publicly disclosed breaches from misconfigured S3 buckets or exposed databases are almost always a 'security IN the cloud' failure on the customer's side — the resulting reputational damage from a breach has real, lasting negative impact on a business's search visibility and trust signals.
- 2
This Model Has No Direct SEO Weight, But Underpins Application Availability
Whether your team correctly manages its side of the shared responsibility model doesn't directly affect rankings, but a resulting security incident that takes a site offline or defaces content absolutely does.
Best Practices
Treat IAM as Your Primary Security IN the Cloud Responsibility
Since AWS never manages your access control decisions, correctly scoped IAM policies (least privilege, no long-lived root credentials) are one of the highest-leverage things a team fully controls and must own diligently.
Never Assume AWS Encrypts Your Data by Default
AWS provides the tools for encryption at rest and in transit, but enabling and correctly configuring them (S3 bucket encryption, RDS encryption, TLS termination) is squarely the customer's responsibility 'in' the cloud.
Frequent Bugs
A public data breach traced to an exposed S3 bucket or database.
This is almost always a customer-side ('security IN the cloud') misconfiguration, not an AWS infrastructure failure — audit S3 bucket policies for public access, and verify database security groups don't expose ports to `0.0.0.0/0`.
A team assumes a compliance certification (like AWS's SOC 2 or ISO 27001) covers their entire application's compliance posture.
AWS's certifications cover 'security OF the cloud' — the infrastructure itself. Your application's compliance also depends entirely on how you configure IAM, encrypt data, and manage access, which are 'security IN the cloud' responsibilities AWS's certifications don't cover.
Real-World Examples
Correctly Splitting Responsibilities for an RDS Database
A team deploying an RDS database relies on AWS to patch the underlying database engine and manage physical infrastructure, while taking full ownership of configuring encryption at rest, IAM database authentication, and security group rules restricting access.
// AWS manages (Security OF the Cloud):
// - Physical hardware, hypervisor, DB engine patching
// Customer manages (Security IN the Cloud):
// - Encryption at rest/in transit, IAM policies, security groups