Amazon Web Services SCS-C02 - AWS Certified Security - Specialty

AWS WAF Geo Match Condition:

Use AWS WAF to create a web access control list (web ACL).

Add a geo match condition to block traffic originating from the specified countries.

Associate Web ACL with CloudFront:

Attach the web ACL to the CloudFront distribution.

Requests from blocked countries will be denied at the CloudFront edge locations, ensuring compliance with data regulation policies.

Advantages of Using AWS WAF:

Cost-effective: Only pay for WAF rules, which are more economical than alternative solutions.

Scalable: Automatically handles global traffic without additional configuration.

Alternative Options:

Using CloudFront's geo-restriction feature (Option C) is also possible but lacks the flexibility and granularity of WAF rules.

AWS WAF Geo Match Conditions

Using AWS WAF with CloudFront

For a company using AWS Organizations that requires centralized management and automatic activation of Amazon GuardDuty across all current and future AWS accounts, setting up a delegated administrator account for GuardDuty is the optimal solution. By enabling GuardDuty in a new account and designating it as the delegated administrator, the company can centrally manage GuardDuty findings and automatically enroll new AWS accounts into GuardDuty as they are created within the organization. This approach ensures consistent threat detection and continuous monitoring across all accounts, aligning with best security practices.

AWS Config is a service that enables you to assess, audit, and evaluate the configurations of your AWS resources. AWS Config continuously monitors and records your AWS resource configurations and allows you to automate the evaluation of recorded configurations against desired configurations.

To evaluate configuration changes to a specific AWS resource and ensure that it meets compliance standards, the security engineer should use AWS Config to detect the configuration changes and to record the latest configuration in case of multiple configuration changes. This will allow the security engineer to view the current state of the resource and its compliance status, as well as its configuration history and timeline.

AWS Config records configuration changes as ConfigurationItems, which are point-in-time snapshots of the resource’s attributes, relationships, and metadata. If multiple configuration changes occur within a short period of time, AWS Config records only the latest ConfigurationItem for that resource. This indicates the cumulative impact of the set of changes on the resource’s configuration.

This solution will meet the requirement in the most operationally efficient way, as it leverages AWS Config’s features to monitor, record, and evaluate resource configurations without requiring additional tools or services.

The other options are incorrect because they either do not record the latest configuration in case of multiple configuration changes (A, C), or do not use a valid service for evaluating resource configurations (D).

Verified References:

https://docs.aws.amazon.com/config/latest/developerguide/WhatIsConfig.html

https://docs.aws.amazon.com/config/latest/developerguide/config-item-table.html

To grant appropriate access to separate modules for read-write and read-only functionality in a serverless application hosted on AWS that uses Amazon Redshift as a data store, a security engineer should configure cluster security groups for each application module to control access to database users that are required for read-only and readwrite, and configure an IAM policy for each module specifying the ARN of an IAM user that allows the GetClusterCredentials API call.

To mitigate a credential stuffing attack against a web-based application behind an Application Load Balancer (ALB), creating an AWS WAF web ACL with a custom rule to block requests containing the known malicious user agent string is an effective solution. This approach allows for precise targeting of the attack vector (the user agent string of the device emulator) without impacting legitimate users. AWS WAF provides the capability to inspect HTTP(S) requests and block those that match defined criteria, such as specific strings in the user agent header, thereby preventing malicious requests from reaching the application.

To configure DNSSEC for a domain registered with Route 53, the most operationally efficient solution is to migrate the zone to Route 53 with DNSSEC signing enabled, create a key-signing key (KSK) that is based on an AWS Key Management Service (AWS KMS) customer managed key, and add a delegation signer (DS) record to the parent zone. This way, Route 53 handles the zone-signing key (ZSK) and the signing of the records in the hosted zone, and the customer only needs to manage the KSK in AWS KMS and provide the DS record to the domain registrar. Option A is incorrect because it does not involve migrating the zone to Route 53, which would simplify the DNSSEC configuration. Option B is incorrect because it creates both a ZSK and a KSK based on AWS KMS customer managed keys, which is unnecessary and less efficient than letting Route 53 manage the ZSK. Option C is incorrect because it does not involve migrating the zone to Route 53, and it requires running the dnssec-signzone command manually, which is less efficient than letting Route 53 sign the zone automatically.Verified References:

https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/domain-configure-dnssec.html

https://aws.amazon.com/about-aws/whats-new/2020/12/announcing-amazon-route-53-support-dnssec/

The correct answer is B. Instruct users to run the aws sts get-session-token CLI command and pass the multi-factor authentication --serial-number and --token-code parameters. Use these resulting values to make API/CLI calls.

According to the AWS documentation1, the aws sts get-session-token CLI command returns a set of temporary credentials for an AWS account or IAM user. The credentials consist of an access key ID, a secret access key, and a security token. These credentials are valid for the specified duration only. The session duration for IAM users can be between 15 minutes and 36 hours, with a default of 12 hours.

You can use the --serial-number and --token-code parameters to provide the MFA device serial number and the MFA code from the device. The MFA device must be associated with the user who is making the get-session-token call. If you do not provide these parameters when your IAM user or role has a policy that requires MFA, you will receive an Access Denied error.

The temporary security credentials that are returned by the get-session-token command can then be used to make subsequent API or CLI calls that require MFA authentication. You can use environment variables or a profile in your AWS CLI configuration file to specify the temporary credentials.

Therefore, this solution will resolve the problem of users being unable to perform EC2 commands using the AWS CLI, while still enforcing MFA.

The other options are incorrect because:

A. Changing the value of aws:MultiFactorAuthPresent to true will not work, because this is a condition key that is evaluated by AWS when a request is made. You cannot set this value manually in your policy or request. You must provide valid MFA information to AWS for this condition key to be true.

C. Implementing federated API/CLI access using SAML 2.0 may work, but it requires more operational effort than using the get-session-token command. You would need to configure a SAML identity provider and trust relationship with AWS, and use a custom SAML client to request temporary credentials from AWS STS. This solution may also introduce additional security risks if the identity provider is compromised.

D. Creating a role and enforcing MFA in the role trust policy may work, but it also requires more operational effort than using the get-session-token command. You would need to create a role for each user or group that needs to perform EC2 commands, and specify a trust policy that requires MFA. You would also need to grant the users permission to assume the role, and instruct them to use the sts assume-role command instead of the get-session-token command.

This option involves creating a VPC Endpoint between the two VPCs that allows private communication between them without going through the internet or exposing any public IP addresses. In this option, a VPC endpoint for Amazon RDS will be established, and an interface VPC endpoint will be created that points to the service endpoint in the Aurora database's VPC. This way, the Lambda functions can use the private IP address of the Aurora database to access it through the VPC endpoint without exposing any public IP addresses or allowing public internet access to the database.

To improve the security at the edge of the solution to defend against a large, layer 7 DDoS attack, the security engineer should do the following:

Configure AWS WAF with a rate-based rule that imposes a rate limit that automatically blocks requests when the rate limit is exceeded. This allows the security engineer to use a rule that tracks the number of requests from a single IP address and blocks subsequent requests if they exceed a specified threshold within a specified time period.