Question 772 of 1,040
Design Secure ArchitecturesmediumMultiple ChoiceObjective-mapped

Mitigating Web Exploits with AWS WAF on CloudFront

This SAA-C03 practice question tests your understanding of design secure architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A public web application is fronted by Amazon CloudFront and an ALB. The team is seeing SQL injection attempts and bursts of malicious HTTP requests that increase origin load. They want to block common web attacks before they reach the ALB. What should they do?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Associate an AWS WAF web ACL with the CloudFront distribution.

AWS WAF is a web application firewall that helps protect web applications from common web exploits like SQL injection and cross-site scripting. By associating an AWS WAF web ACL with the CloudFront distribution, you can inspect and filter HTTP(S) requests at the edge before they reach the ALB, reducing origin load and blocking malicious traffic early. This is the recommended approach for defending against layer 7 attacks at the CDN level.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Associate an AWS WAF web ACL with the CloudFront distribution.

    Why this is correct

    AWS WAF is the correct service for filtering HTTP(S) requests based on patterns such as SQL injection, bad bots, and rate-based abuse. When associated with CloudFront, the filtering happens at the edge before traffic reaches the ALB and origin, reducing load and blocking malicious requests earlier in the path. Shield Standard is already included for basic DDoS protection, but WAF is the component that provides the application-layer controls needed here.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Add an inbound security group rule to the ALB for the attacker IP ranges.

    Why it's wrong here

    Security groups cannot inspect HTTP payloads for SQL injection or block application-layer request patterns effectively.

    When this WOULD be correct

    If the question asked to block all traffic from a specific IP range at the network level before it reaches the ALB, adding an inbound security group rule denying that IP range would be correct. For example: 'Block all requests from a known malicious IP range at the ALB.'

  • Use a network ACL to inspect and block SQL statements in the request body.

    Why it's wrong here

    Network ACLs operate at the packet and port level, not at the HTTP content level needed for SQL injection filtering.

    When this WOULD be correct

    A question asks to block traffic from a specific IP range at the subnet boundary for a VPC, where application-layer inspection is not required.

  • Enable Amazon KMS encryption on the ALB listener certificates.

    Why it's wrong here

    TLS encryption protects data in transit, but it does not stop malicious request content or reduce attack traffic volume.

    When this WOULD be correct

    A question asks how to enforce encryption for data in transit between the ALB and clients, or to meet compliance requirements for TLS termination using customer-managed keys, where the ALB must use certificates encrypted with KMS.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The SAA-C03 exam frequently reuses these exact scenarios with slightly different constraints.

Associate an AWS WAF web ACL with the CloudFront distribution.Correct answer

Why this is correct

AWS WAF is the correct service for filtering HTTP(S) requests based on patterns such as SQL injection, bad bots, and rate-based abuse. When associated with CloudFront, the filtering happens at the edge before traffic reaches the ALB and origin, reducing load and blocking malicious requests earlier in the path. Shield Standard is already included for basic DDoS protection, but WAF is the component that provides the application-layer controls needed here.

Add an inbound security group rule to the ALB for the attacker IP ranges.Wrong answer — click to see why

Why this is wrong here

Security group rules operate at the network/transport layer and cannot inspect application-layer content like SQL injection payloads. They only filter based on IP, port, and protocol, not HTTP request bodies.

★ When this WOULD be the correct answer

If the question asked to block all traffic from a specific IP range at the network level before it reaches the ALB, adding an inbound security group rule denying that IP range would be correct. For example: 'Block all requests from a known malicious IP range at the ALB.'

Why candidates choose this

Candidates may think security groups can block attacks because they are a common security control, but they confuse network-layer filtering with application-layer inspection that WAF provides.

Use a network ACL to inspect and block SQL statements in the request body.Wrong answer — click to see why

Why this is wrong here

Network ACLs operate at the subnet level and cannot inspect application-layer content like SQL statements in request bodies; they only filter based on IP, port, and protocol.

★ When this WOULD be the correct answer

A question asks to block traffic from a specific IP range at the subnet boundary for a VPC, where application-layer inspection is not required.

Why candidates choose this

Candidates may confuse network ACLs with WAF, thinking ACLs can perform deep packet inspection, or they overestimate the capabilities of network-layer filtering.

Enable Amazon KMS encryption on the ALB listener certificates.Wrong answer — click to see why

Why this is wrong here

KMS encryption on ALB listener certificates secures data in transit but does not inspect or block SQL injection or malicious HTTP requests; it provides no web attack protection.

★ When this WOULD be the correct answer

A question asks how to enforce encryption for data in transit between the ALB and clients, or to meet compliance requirements for TLS termination using customer-managed keys, where the ALB must use certificates encrypted with KMS.

Why candidates choose this

Candidates may confuse encryption with security controls, thinking that encrypting traffic somehow prevents attacks, or they may overestimate the scope of KMS capabilities.

Analysis generated from the official SAA-C03blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often confuse network-layer controls (security groups, NACLs) with application-layer protection, mistakenly thinking they can block SQL injection at the network level, when only a WAF can inspect HTTP request bodies for such attacks.

Detailed technical explanation

How to think about this question

AWS WAF integrates with CloudFront to evaluate incoming requests against rules in a web ACL before they reach the origin. The SQL injection match condition uses pattern matching and keyword analysis on the request body, query strings, or URI to detect malicious payloads. In a real-world scenario, this edge-based filtering reduces the load on the ALB and backend instances by dropping malicious traffic at CloudFront's over 400 points of presence, which is critical for handling burst attacks like HTTP floods.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.

Visual reference

Source Router + ACL permit 10.0.0.0/8 deny any Server 10.0.0.5 ✓ 192.168.1.1 ✗ dropped ACLs evaluate top-down; first match wins — implicit deny all at end

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this SAA-C03 question test?

Design Secure Architectures — This question tests Design Secure Architectures — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Associate an AWS WAF web ACL with the CloudFront distribution. — AWS WAF is a web application firewall that helps protect web applications from common web exploits like SQL injection and cross-site scripting. By associating an AWS WAF web ACL with the CloudFront distribution, you can inspect and filter HTTP(S) requests at the edge before they reach the ALB, reducing origin load and blocking malicious traffic early. This is the recommended approach for defending against layer 7 attacks at the CDN level.

What should I do if I get this SAA-C03 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Same concept, more angles

1 more ways this is tested on SAA-C03

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. Your organization hosts an internet-facing application behind an Amazon CloudFront distribution. You want to mitigate common web exploits (for example, SQL injection and XSS) at the edge. Which action is the most appropriate way to do this using AWS services?

easy
  • A.Create an AWS WAF web ACL using managed rule sets and associate it with the CloudFront distribution.
  • B.Add inbound rules to the security group so that only port 443 is open from the internet.
  • C.Enable AWS Shield Advanced to block SQL injection and XSS.
  • D.Restrict IAM permissions for the application’s EC2 instances so that SQL injection payloads cannot be executed.

Why A: AWS WAF is a web application firewall that helps protect web applications from common web exploits like SQL injection and cross-site scripting (XSS). By creating a web ACL with managed rule sets (e.g., the AWS Managed Rules for SQL injection and XSS) and associating it with your CloudFront distribution, you can inspect incoming HTTP/HTTPS requests at the edge and block malicious payloads before they reach your origin. This is the most appropriate and scalable way to mitigate these threats at the edge.

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Last reviewed: Jun 11, 2026

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This SAA-C03 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAA-C03 exam.