Helmet for security headers in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import Helmet in an Express app.

Express

const express = require('express');
const [1] = require('helmet');
const app = express();

Drag options to blanks, or click blank then click option'

Ahelmet

Bexpress

Ccors

Dmorgan

Attempts:

3 left

💡 Hint

Common Mistakes

Importing 'express' instead of 'helmet'.

Forgetting to assign the require to a variable.

You import Helmet by requiring 'helmet' and assigning it to a variable, usually named helmet.

2fill in blank

medium

Complete the code to use Helmet middleware in the Express app.

Express

const app = express();
app.[1](helmet());

Drag options to blanks, or click blank then click option'

Ause

Blisten

Cget

Dpost

Attempts:

3 left

💡 Hint

Common Mistakes

Using app.listen instead of app.use.

Trying to use app.get or app.post for middleware.

To add middleware in Express, you use app.use(). Helmet is middleware, so you call app.use(helmet()).

3fill in blank

hard

Fix the error in the code to correctly set Helmet's contentSecurityPolicy option.

Express

app.use(helmet({ contentSecurityPolicy: [1] }));

Drag options to blanks, or click blank then click option'

A{}

Bfalse

C'default-src self'

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string instead of false.

Passing true which enables default policy.

To disable the contentSecurityPolicy in Helmet, you set contentSecurityPolicy: false. Using true or a string causes errors.

4fill in blank

hard

Fill both blanks to configure Helmet to disable frameguard and enable hsts with maxAge 1 year.

Express

app.use(helmet({ frameguard: [1], hsts: { maxAge: [2] } }));

Drag options to blanks, or click blank then click option'

Afalse

Btrue

C31536000

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using true to disable frameguard.

Setting maxAge to 0 which disables hsts.

Setting frameguard to false disables it. The hsts maxAge is in seconds; 1 year is 31536000 seconds.

5fill in blank

hard

Fill all three blanks to create a Helmet config that disables dnsPrefetchControl, enables referrerPolicy with 'no-referrer', and sets crossOriginEmbedderPolicy to true.

Express

app.use(helmet({ dnsPrefetchControl: [1], referrerPolicy: { policy: '[2]' }, crossOriginEmbedderPolicy: [3] }));

Drag options to blanks, or click blank then click option'

Afalse

Bno-referrer

Ctrue

Dstrict-origin

Attempts:

3 left

💡 Hint

Common Mistakes

Using true to disable dnsPrefetchControl.

Using wrong string for referrerPolicy.

Setting crossOriginEmbedderPolicy to false.

To disable dnsPrefetchControl, set it to false. The referrerPolicy string 'no-referrer' disables sending referrer info. crossOriginEmbedderPolicy is a boolean, so true enables it.

Practice

1. What is the main purpose of using helmet in an Express app?

easy

A. To add security headers that protect the app from common web attacks

B. To handle database connections securely

C. To improve the app's performance by caching

D. To manage user authentication and sessions

Solution

1. Step 1: Understand Helmet's role

   Helmet is a middleware that adds HTTP headers to improve security.

2. Step 2: Identify the main benefit

   These headers help protect against attacks like cross-site scripting and clickjacking.

3. Final Answer:

   To add security headers that protect the app from common web attacks -> Option A

4. Quick Check:

   Helmet adds security headers = D [OK]

Hint: Helmet = security headers for Express apps [OK]

Common Mistakes:

• Confusing Helmet with authentication middleware
• Thinking Helmet manages database or caching
• Assuming Helmet improves app speed

2. Which of the following is the correct way to use Helmet in an Express app?

easy

A. import helmet from 'helmet'; app.use(helmet());

B. const helmet = require('helmet'); app.use(helmet());

C. const helmet = require('helmet'); app.use(helmet);

D. import helmet from 'helmet'; app.use(helmet);

Solution

1. Step 1: Check import syntax

   In CommonJS, use const helmet = require('helmet');. In ES modules, use import helmet from 'helmet';.

2. Step 2: Use helmet as middleware function

   Helmet must be called as a function: helmet(), then passed to app.use().

3. Final Answer:

   const helmet = require('helmet'); app.use(helmet()); -> Option B

4. Quick Check:

   Require + call helmet() = A [OK]

Hint: Require helmet and call it as a function in app.use() [OK]

Common Mistakes:

• Forgetting to call helmet() as a function
• Using require with ES module import style
• Passing helmet without parentheses to app.use

3. Given this Express code snippet, what HTTP header will be set by Helmet by default?

import express from 'express';
import helmet from 'helmet';
const app = express();
app.use(helmet());
app.get('/', (req, res) => res.send('Hello'));
app.listen(3000);

medium

A. Content-Security-Policy

B. X-Powered-By

C. Access-Control-Allow-Origin

D. X-DNS-Prefetch-Control

Solution

1. Step 1: Recall Helmet default headers

   Helmet sets several headers by default, including X-DNS-Prefetch-Control to control DNS prefetching.

2. Step 2: Identify headers not set by default

   Content-Security-Policy is not set by default; X-Powered-By is removed by Helmet; Access-Control-Allow-Origin is for CORS, not Helmet.

3. Final Answer:

   X-DNS-Prefetch-Control -> Option D

4. Quick Check:

   Helmet default header = X-DNS-Prefetch-Control [OK]

Hint: Helmet sets X-DNS-Prefetch-Control by default [OK]

Common Mistakes:

• Assuming Content-Security-Policy is set by default
• Thinking Helmet adds CORS headers
• Confusing X-Powered-By removal with setting

4. What is wrong with this code snippet using Helmet?

import express from 'express';
import helmet from 'helmet';
const app = express();
app.use(helmet);
app.listen(3000);

medium

A. Helmet middleware is not called as a function

B. Helmet is not imported correctly

C. Express app is not created properly

D. app.listen is missing a callback

Solution

1. Step 1: Check Helmet usage

   The code uses app.use(helmet); but Helmet must be called as a function: helmet().

2. Step 2: Verify other parts

   Helmet import is valid; Express app creation is valid; app.listen callback is optional.

3. Final Answer:

   Helmet middleware is not called as a function -> Option A

4. Quick Check:

   Use helmet() in app.use() [OK]

Hint: Always call helmet() before app.use() [OK]

Common Mistakes:

• Passing helmet without parentheses to app.use
• Confusing import styles
• Thinking app.listen needs a callback

5. You want to disable the Content-Security-Policy header in Helmet but keep all other default headers. Which code correctly achieves this?

hard

A. app.use(helmet({ disable: ['contentSecurityPolicy'] }));

B. app.use(helmet.disable('contentSecurityPolicy'));

C. app.use(helmet({ contentSecurityPolicy: false }));

D. app.use(helmet().disable('contentSecurityPolicy'));

Solution

1. Step 1: Understand Helmet options

   Helmet allows disabling specific headers by passing options with the header name set to false.

2. Step 2: Identify correct syntax

   The correct way is helmet({ contentSecurityPolicy: false }). Other options shown are invalid methods or syntax.

3. Final Answer:

   app.use(helmet({ contentSecurityPolicy: false })); -> Option C

4. Quick Check:

   Disable header via option false = A [OK]

Hint: Disable headers by setting option to false in helmet() [OK]

Common Mistakes:

• Trying to call disable() method on helmet
• Passing disable array option (not supported)
• Calling disable on helmet() instance