AWS Certified Security – Specialty — Question 355

A company has deployed Amazon GuardDuty and now wants to implement automation for potential threats. The company has decided to start with RDP brute force attacks that come from Amazon EC2 instances in the company’s AWS environment. A security engineer needs to implement a solution that blocks the detected communication from a suspicious instance until investigation and potential remediation can occur.

Which solution will meet these requirements?

Answer options

• A. Configure GuardDuty to send the event to an Amazon Kinesis data stream. Process the event with an Amazon Kinesis Data Analytics for Apache Flink application that sends a notification to the company through Amazon Simple Notification Service (Amazon SNS). Add rules to the network ACL to block traffic to and from the suspicious instance.
• B. Configure GuardDuty to send the event to Amazon EventBridge (Amazon CloudWatch Events). Deploy an AWS WAF web ACL. Process the event with an AWS Lambda function that sends a notification to the company through Amazon Simple Notification Service (Amazon SNS) and adds a web ACL rule to block traffic to and from the suspicious instance.
• C. Enable AWS Security Hub to ingest GuardDuty findings and send the event to Amazon EventBridge (Amazon CloudWatch Events). Deploy AWS Network Firewall. Process the event with an AWS Lambda function that adds a rule to a Network Firewall firewall policy to block traffic to and from the suspicious instance.
• D. Enable AWS Security Hub to ingest GuardDuty findings. Configure an Amazon Kinesis data stream as an event destination for Security Hub. Process the event with an AWS Lambda function that replaces the security group of the suspicious instance with a security group that does not allow any connections.

Correct answer: C

Explanation

Integrating AWS Security Hub with GuardDuty allows for centralized security alerts, which can then trigger Amazon EventBridge to run an AWS Lambda function. This Lambda function can programmatically update AWS Network Firewall policies to block traffic to and from the suspicious instance, effectively neutralizing the threat. Other options are incorrect because AWS WAF is designed for HTTP/HTTPS traffic rather than RDP, and Kinesis Data Analytics is unnecessarily complex for this automation scenario.