WAF with Application Gateway in Azure - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Web Application Firewall (WAF) in Azure Application Gateway?

A WAF is a security feature in Azure Application Gateway that protects web applications by filtering and monitoring HTTP traffic to block malicious requests like SQL injection or cross-site scripting.

beginner

How does Azure Application Gateway WAF protect your web app?

It inspects incoming web traffic and blocks attacks based on predefined security rules, helping to prevent common web vulnerabilities and attacks.

intermediate

What is the difference between Detection and Prevention modes in WAF?

Detection mode only logs potential threats without blocking them, while Prevention mode actively blocks malicious traffic to protect the application.

beginner

Why is it important to enable WAF on Application Gateway for public-facing web apps?

Because public web apps are exposed to the internet and can be targeted by attackers, WAF helps protect them by filtering harmful traffic before it reaches the app.

intermediate

What are custom WAF rules in Azure Application Gateway?

Custom WAF rules let you create specific conditions to allow or block traffic based on your app’s unique needs, adding extra control beyond default rules.

What does Azure Application Gateway WAF primarily protect against?

A Data storage corruption

B Network hardware failures

C Web application attacks like SQL injection

D User password theft

WAF focuses on protecting web apps from attacks such as SQL injection and cross-site scripting.

Which WAF mode blocks malicious traffic instead of just logging it?

A Detection mode

B Prevention mode

C Monitoring mode

D Passive mode

Prevention mode actively blocks malicious requests, while Detection mode only logs them.

Where is Azure Application Gateway WAF deployed in relation to your web app?

A Between users and the web app

B Inside the web app code

C On the user's device

D On the database server

The WAF is placed in front of the web app to inspect and filter incoming traffic.

What can you customize in Azure Application Gateway WAF to fit your app’s needs?

A Custom WAF rules

B User interface themes

C Database schemas

D Network cables

Custom WAF rules allow you to define specific traffic filtering conditions.

Why should you enable WAF for public-facing web applications?

A To improve internet speed

B To increase user logins

C To reduce server storage

D To protect against web attacks

Public web apps are exposed to attacks, so WAF helps protect them by filtering harmful traffic.

Explain how Azure Application Gateway WAF protects a web application from attacks.

Think about how a security guard checks visitors before they enter a building.

Describe the difference between Detection and Prevention modes in Azure Application Gateway WAF.

One mode watches quietly, the other acts to stop danger.

Practice

1. What is the main purpose of enabling WAF (Web Application Firewall) on an Azure Application Gateway?

easy

A. To provide a database backup solution

B. To protect web applications from common web attacks like SQL injection and cross-site scripting

C. To increase the speed of the web application by caching content

D. To monitor network traffic at the virtual network level

Solution

1. Step 1: Understand WAF's role

   WAF is designed to protect web apps by filtering and monitoring HTTP traffic to block common attacks.

2. Step 2: Compare options

   Only To protect web applications from common web attacks like SQL injection and cross-site scripting describes protection from web attacks, which is the core function of WAF.

3. Final Answer:

   To protect web applications from common web attacks like SQL injection and cross-site scripting -> Option B

4. Quick Check:

   WAF protects web apps = C [OK]

Hint: WAF blocks web attacks, not speeds or backups [OK]

Common Mistakes:

• Confusing WAF with caching or backup services
• Thinking WAF monitors network traffic broadly
• Assuming WAF improves app speed

2. Which of the following is the correct way to enable WAF on an Azure Application Gateway using ARM template syntax?

easy

A. "sku": { "name": "WAF_v2" }, "wafConfiguration": { "enabled": true, "firewallMode": "Prevention" }

B. "sku": { "name": "Standard_v2" }, "wafConfiguration": { "enabled": true }

C. "sku": { "name": "Basic" }, "wafConfiguration": { "enabled": false }

D. "sku": { "name": "WAF_v1" }, "wafConfiguration": { "enabled": false, "firewallMode": "Detection" }

Solution

1. Step 1: Identify correct SKU for WAF

   WAF requires SKU like "WAF_v2" or "WAF_v1"; Standard_v2 or Basic do not enable WAF.

2. Step 2: Check WAF configuration

   WAF must be enabled with "enabled": true and a valid firewallMode like "Prevention" or "Detection".

3. Final Answer:

   "sku": { "name": "WAF_v2" }, "wafConfiguration": { "enabled": true, "firewallMode": "Prevention" } -> Option A

4. Quick Check:

   WAF SKU + enabled true + mode = A [OK]

Hint: WAF needs WAF SKU and enabled true [OK]

Common Mistakes:

• Using Standard or Basic SKU without WAF
• Setting enabled to false when enabling WAF
• Omitting firewallMode or using invalid values

3. Given this snippet of ARM template for Application Gateway WAF configuration:

{
  "sku": { "name": "WAF_v2" },
  "wafConfiguration": {
    "enabled": true,
    "firewallMode": "Detection"
  }
}

What will be the behavior of the Application Gateway regarding detected threats?

medium

A. It will log detected threats but allow traffic to pass through

B. It will block detected threats and return an error to clients

C. It will ignore detected threats and not log them

D. It will shut down the Application Gateway on threat detection

Solution

1. Step 1: Understand firewallMode 'Detection'

   Detection mode means WAF monitors and logs threats but does not block traffic.

2. Step 2: Compare options with behavior

   Only It will log detected threats but allow traffic to pass through matches detection mode behavior: logging threats but allowing traffic.

3. Final Answer:

   It will log detected threats but allow traffic to pass through -> Option A

4. Quick Check:

   Detection mode = log only, no block = B [OK]

Hint: Detection mode logs but does not block [OK]

Common Mistakes:

• Confusing Detection with Prevention mode
• Assuming threats are blocked in Detection mode
• Thinking Application Gateway shuts down on threats

4. You configured WAF on Application Gateway with this snippet:

{
  "sku": { "name": "WAF_v2" },
  "wafConfiguration": {
    "enabled": true,
    "firewallMode": "Prevention"
  }
}

But the WAF is not blocking malicious requests. What is the most likely cause?

medium

A. The Application Gateway is missing a listener configuration

B. The SKU name "WAF_v2" does not support prevention mode

C. The WAF policy is not associated with the Application Gateway

D. The firewallMode should be set to Detection to block requests

Solution

1. Step 1: Check WAF policy association

   Even if WAF is enabled, it must have a WAF policy linked to enforce rules and block threats.

2. Step 2: Validate other options

   Listener is required but unrelated to blocking; prevention mode blocks; WAF_v2 supports prevention mode.

3. Final Answer:

   The WAF policy is not associated with the Application Gateway -> Option C

4. Quick Check:

   WAF policy association needed to block = D [OK]

Hint: WAF needs policy linked to block threats [OK]

Common Mistakes:

• Confusing detection and prevention modes
• Forgetting to associate WAF policy
• Assuming SKU limits prevention mode

5. You want to protect your web app with Azure Application Gateway WAF in prevention mode but also need to monitor false positives before blocking. What is the best approach to achieve this?

hard

A. Use Basic SKU Application Gateway with WAF enabled

B. Enable WAF in prevention mode immediately and block all detected threats

C. Disable WAF and rely on network security groups for protection

D. Enable WAF in detection mode first, review logs, then switch to prevention mode

Solution

1. Step 1: Understand prevention vs detection modes

   Prevention mode blocks threats immediately; detection mode only logs them for review.

2. Step 2: Plan safe deployment

   Start with detection mode to identify false positives, then switch to prevention to block real threats safely.

3. Final Answer:

   Enable WAF in detection mode first, review logs, then switch to prevention mode -> Option D

4. Quick Check:

   Detect first, then prevent = A [OK]

Hint: Detect first, then switch to prevention mode [OK]

Common Mistakes:

• Blocking immediately without monitoring false positives
• Disabling WAF and relying on unrelated protections
• Using Basic SKU which does not support WAF