SCS-C02 Infrastructure Security Practice Test 21 — 15 Questions

Question 1

A company is deploying a web application on EC2 instances behind an Application Load Balancer. The security team requires that all traffic between the ALB and the EC2 instances be encrypted. Which configuration should the engineer implement?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Configure the ALB listener with HTTPS protocol and the target group with HTTPS protocol, and install SSL certificates on the EC2 instances.. It ensures end-to-end encryption between the ALB and EC2 instances. The ALB listener uses HTTPS to terminate client SSL/TLS, and the target group uses HTTPS to re-encrypt traffic to the instances, requiring SSL certificates on the EC2 instances to decrypt and re-encrypt. This satisfies the security requirement that all traffic between the ALB and EC2 instances be encrypted.

Answer

Configure the ALB listener with HTTP protocol and the target group with HTTP protocol, then use a security group to restrict traffic.

Answer

Configure the ALB listener with HTTPS protocol and the target group with HTTP protocol.

Answer

Configure the ALB listener with TCP protocol and the target group with TCP protocol, then install SSL certificates on the EC2 instances.

Question 2

A company uses AWS Key Management Service (KMS) to encrypt data at rest. The security team needs to ensure that only specific IAM roles can use a particular KMS key to encrypt and decrypt data. What is the most secure way to achieve this?

Accepted Answer

Create a KMS key policy that grants access only to the specific IAM roles using the kms:CallerArn condition.. Using a key policy with a condition for the kms:CallerArn attribute restricts usage to the specified roles. Option A is wrong because IAM policies alone cannot restrict KMS key usage if the key policy allows all principals. Option C is wrong because key policy with Principal "*" grants access to all, even with a condition. Option D is wrong because a condition for the IAM role's ARN is not a standard KMS condition key.

Answer

Create an IAM policy that allows kms:Encrypt and kms:Decrypt for the roles and attach it to the roles.

Answer

Create a KMS key policy that grants access to the account and use IAM policies to restrict the roles.

Answer

Create a KMS key policy with Principal "*" and a condition that the request originates from the roles.

Question 3

A security engineer is designing a secure VPC architecture. Which THREE components should be used to implement defense in depth? (Choose three.)

Accepted Answer

Security groups. Security groups (C) are stateful virtual firewalls that control inbound and outbound traffic at the instance level. They operate at the network interface (ENI) level, allowing only explicitly permitted traffic and automatically allowing return traffic for permitted sessions. This provides a critical layer of host-level defense within the VPC.

Answer

VPN connection

Answer

Internet gateway

Question 4

A company wants to restrict access to an S3 bucket so that only traffic from a specific VPC can read objects. The VPC has a VPC endpoint for S3 configured. Which policy should be attached to the bucket?

Accepted Answer

{"Effect":"Allow","Principal":"*","Action":"s3:GetObject","Resource":"arn:aws:s3:::bucket/*","Condition":{"StringEquals":{"aws:SourceVpce":"vpce-11111111"}}}. It uses the `aws:SourceVpce` condition key to restrict access to the S3 bucket exclusively to requests originating from the specified VPC endpoint (vpce-11111111). This ensures that only traffic routed through that VPC endpoint, which is attached to the specific VPC, can perform `s3:GetObject` actions, effectively limiting access to the VPC's private network.

Answer

{"Effect":"Allow","Principal":"*","Action":"s3:GetObject","Resource":"arn:aws:s3:::bucket/*","Condition":{"StringEquals":{"aws:VpcSourceIp":"10.0.0.0/16"}}}

Answer

{"Effect":"Allow","Principal":"*","Action":"s3:GetObject","Resource":"arn:aws:s3:::bucket/*","Condition":{"StringEquals":{"aws:SourceVpc":"vpc-12345678"}}}

Answer

{"Effect":"Allow","Principal":"*","Action":"s3:GetObject","Resource":"arn:aws:s3:::bucket/*","Condition":{"IpAddress":{"aws:SourceIp":"10.0.0.0/16"}}}

Question 5

A Security Engineer is designing a network architecture for a multi-tier application. The web tier must be accessible from the internet, while the application tier should only be accessible from the web tier, and the database tier only from the application tier. All tiers are in the same VPC. Which configuration meets these requirements with minimal administrative overhead?

Accepted Answer

Use security groups with inbound rules that reference the security group of the previous tier.. Security groups are stateful and can reference other security groups as a source in inbound rules, allowing traffic from any instance associated with the referenced security group regardless of IP address changes. This creates a logical dependency chain (web SG → app SG → db SG) that enforces the required tier-to-tier access with zero maintenance when instances scale or subnets change. Option D meets the requirement with minimal administrative overhead because security group references automatically adapt to dynamic environments.

Answer

Use network ACLs with inbound rules that reference the prefix list of the previous tier's subnets.

Answer

Use network ACLs with inbound rules that allow traffic from the previous tier's subnet CIDR.

Answer

Use security groups with inbound rules that allow traffic from the previous tier's public IP addresses.

Question 6

A company wants to encrypt data at rest in an Amazon S3 bucket. Which AWS service can centrally manage the encryption keys?

Accepted Answer

AWS Key Management Service (AWS KMS). AWS Key Management Service (AWS KMS) is the correct service because it is a fully managed, centralized service that allows you to create, manage, and control the encryption keys used to encrypt data at rest in Amazon S3. S3 integrates directly with KMS via Server-Side Encryption with AWS KMS (SSE-KMS), enabling you to use customer managed keys (CMKs) or AWS managed keys to enforce granular access control and audit key usage through AWS CloudTrail.

Answer

AWS CloudHSM

Answer

AWS Certificate Manager (ACM)

Answer

AWS Secrets Manager

Question 7

A company is using AWS Transit Gateway to connect multiple VPCs and on-premises networks. The Security Engineer needs to ensure that traffic between VPCs is inspected by a central network appliance. Which architecture should the Engineer implement?

Accepted Answer

Use Transit Gateway with appliance mode enabled on the attachments to the inspection VPC, and route inter-VPC traffic through the inspection VPC.. Enabling appliance mode on the Transit Gateway attachments to the inspection VPC forces the Transit Gateway to preserve the source and destination MAC addresses of packets, ensuring that asymmetric routing does not cause the network appliance to drop traffic. By routing inter-VPC traffic through the inspection VPC, the appliance can inspect all packets, and appliance mode ensures that return traffic is sent back through the same appliance, maintaining stateful inspection.

Answer

Use VPC Peering connections between all VPCs and route traffic through the inspection VPC.

Answer

Place the network appliance in a public subnet of the inspection VPC and use internet gateways for routing.

Answer

Use Transit Gateway with route tables that point to the network appliance's ENI for all inter-VPC traffic.

Question 8

A Security Engineer needs to block SSH traffic (port 22) from the internet to all EC2 instances in a VPC. Which approach is the most secure and scalable?

Accepted Answer

Add a network ACL rule to deny inbound traffic on port 22 from 0.0.0.0/0 at the subnet level.. Network ACLs (NACLs) are stateless and operate at the subnet level, allowing you to explicitly deny inbound SSH traffic from 0.0.0.0/0. This approach is more secure and scalable than security group rules because NACLs can block traffic before it reaches the instance, and they support explicit deny rules, which security groups do not. Security groups only support allow rules, so you cannot add a deny rule to block SSH traffic; you must omit the allow rule, which is less explicit and can be accidentally overridden.

Answer

Add a security group rule to deny inbound traffic on port 22 from 0.0.0.0/0.

Answer

Add a network ACL rule to allow inbound traffic on port 22 from 0.0.0.0/0 and then add a deny rule for the same traffic.

Answer

Add a security group rule to block inbound traffic on port 22 from 0.0.0.0/0 at the VPC level.

Question 9

A Security Engineer is configuring a VPC with a public subnet for a web server and a private subnet for a database. The web server needs to download patches from the internet. Which TWO actions should the Engineer take to allow the web server internet access without exposing the database to the internet?

Accepted Answer

Create a NAT Gateway in the public subnet.. A NAT Gateway in the public subnet allows instances in the private subnet to initiate outbound IPv4 traffic to the internet (e.g., to download patches) while preventing unsolicited inbound connections from the internet. By adding a route in the private subnet's route table that points 0.0.0.0/0 to the NAT Gateway, the web server's outbound traffic is forwarded to the NAT Gateway, which then uses the Internet Gateway to reach the internet. The database remains isolated because it has no direct route to the Internet Gateway and no public IP address.

Answer

Create a bastion host in the public subnet and configure the web server to use it as a proxy.

Answer

Create a VPC endpoint for Amazon S3.

Answer

Attach an Internet Gateway to the VPC and add a route to the Internet Gateway in the private subnet's route table.

Question 10

A company is using Amazon EC2 instances in a VPC with a security group that allows inbound SSH from 0.0.0.0/0. A security engineer needs to restrict SSH access to only the company's public IP range (203.0.113.0/24) while maintaining all other existing rules. What is the MOST efficient way to accomplish this?

Accepted Answer

Modify the existing security group rule to change the source from 0.0.0.0/0 to 203.0.113.0/24.. Modifying the existing security group rule's source from 0.0.0.0/0 to 203.0.113.0/24 directly restricts inbound SSH to the company's public IP range without affecting any other rules. Security groups are stateful and rule changes apply immediately, making this the most efficient approach as it requires only a single edit to the existing rule.

Answer

Disable SSH and use AWS Systems Manager Session Manager to connect to instances.

Answer

Create a network ACL with an inbound rule allowing SSH from 203.0.113.0/24 and deny all other traffic.

Answer

Create a new security group rule allowing SSH from 203.0.113.0/24 and keep the existing rule.

Question 11

A security engineer is designing a multi-tier web application on AWS. The web tier must be accessible from the internet, but the application tier should be accessible only from the web tier. The database tier should be accessible only from the application tier. Which combination of security groups provides the MOST secure configuration?

Accepted Answer

Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from App SG security group ID.. It uses security group IDs as the source for inbound rules, which allows traffic only from instances associated with the specified security group, regardless of their IP addresses. This provides a dynamic and secure way to control traffic between tiers, as security group IDs are resolved at the instance level and automatically adapt to changes in instance membership. By contrast, using CIDR blocks (as in options A and C) is less secure because it relies on static IP ranges that may not accurately reflect the actual instances in the web or app tiers, and option B is overly permissive by allowing all traffic from the web SG.

Answer

Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG CIDR. DB SG: allow MySQL from App SG CIDR.

Answer

Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow all traffic from Web SG. DB SG: allow MySQL from App SG.

Answer

Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from 10.0.0.0/24.

Question 12

A security engineer is configuring a VPC for a highly sensitive application. The VPC must not have a route to the internet, but the application needs to periodically download security patches from a specific domain (patches.example.com). Which solution meets these requirements with minimal operational overhead?

Accepted Answer

Use a VPC endpoint for Amazon S3 and DynamoDB to download patches.. It uses VPC endpoints for Amazon S3 (and optionally DynamoDB) to provide private connectivity to AWS services without requiring an internet gateway. By storing the security patches in an S3 bucket with a custom domain alias (e.g., patches.example.com), the application can download patches through the VPC endpoint, meeting the requirement of no internet route and minimizing operational overhead. Options A and D require an internet gateway, which creates a route to the internet. Option C does not provide access to an external domain like patches.example.com.

Answer

Launch a proxy server in a public subnet and configure the application to use the proxy.

Answer

Create a VPC interface endpoint for AWS Systems Manager and use Systems Manager Patch Manager to apply patches.

Answer

Deploy a NAT gateway in a public subnet and add a route to the NAT gateway for the private subnet.

Question 13

A company uses AWS Organizations to manage multiple accounts. The security team wants to ensure that no resources can be created in a specific AWS Region except for the us-east-1 Region. Which policy type should the security team use?

Accepted Answer

Service control policy (SCP). Service control policies (SCPs) are the correct choice because they allow you to centrally control the maximum available permissions for all accounts in an AWS Organization. By applying an SCP that denies all actions in a specific region (except us-east-1), the security team can enforce a region restriction across all member accounts, regardless of any IAM policies attached to users or roles. SCPs do not grant permissions themselves but act as a guardrail that limits what IAM policies can allow.

Answer

IAM permissions boundary

Answer

IAM policy applied to the root user

Answer

Resource-based policy

Question 14

A company is designing a shared services VPC architecture with multiple VPCs connected via a transit gateway. The security engineer needs to ensure that all traffic between VPCs is inspected by a centralized firewall appliance deployed in the shared services VPC. What configuration is required?

Accepted Answer

Configure transit gateway route tables to route all inter-VPC traffic through the firewall appliance.. A transit gateway can use separate route tables to control traffic flow. By configuring the transit gateway route tables to point the default route (0.0.0.0/0) or specific inter-VPC CIDR ranges to a network interface of the centralized firewall appliance in the shared services VPC, all traffic between VPCs is forced through the firewall for inspection. This design ensures that the firewall acts as a central inspection point without requiring VPC peering or complex routing.

Answer

Create VPC peering connections between each VPC and the shared services VPC.

Answer

Use security groups to route traffic through the firewall.

Answer

Deploy a Gateway Load Balancer (GWLB) in the shared services VPC and register the firewall as a target.

Question 15

A company is deploying a web application on EC2 instances behind an Application Load Balancer. The security team requires that all traffic between the ALB and the EC2 instances be encrypted. Which configuration should the engineer implement?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

AWS Shield Advanced. AWS WAF (Option D) can be associated with an ALB to filter web requests and protect against common exploits like SQL injection and cross-site scripting. AWS Shield Advanced (Option B) provides enhanced DDoS protection and integrates with WAF for additional layer 7 protections. Option A is wrong because GuardDuty is a threat detection service, not an inline web application firewall. Option C is wrong because Network ACLs operate at the subnet level and do not provide application-layer filtering. Option E is wrong because CloudFront is a CDN, and while it can be used with WAF, it alone does not provide WAF rules.

Answer

Amazon GuardDuty

Answer

Network ACLs

Answer

Amazon CloudFront