Content Security Policy in Django - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Content Security Policy (CSP)?

Content Security Policy is a security feature that helps prevent attacks like cross-site scripting (XSS) by controlling which resources (scripts, styles, images) a web page can load.

intermediate

How do you add a Content Security Policy header in Django?

You can add CSP headers in Django by using middleware or third-party packages like django-csp, which lets you define policies in your settings to control resource loading.

beginner

What does the directive script-src 'self' mean in a CSP?

It means the page is only allowed to load and run scripts that come from the same origin (domain) as the page itself, blocking scripts from other sources.

intermediate

Why is it important to avoid using unsafe-inline in CSP?

Using unsafe-inline allows inline scripts, which can open doors to XSS attacks. Avoiding it makes your site safer by only allowing trusted external scripts.

beginner

Name a common Django package used to implement CSP easily.

The package django-csp is commonly used to add and manage Content Security Policy headers in Django projects.

What is the main purpose of Content Security Policy in Django?

A To control which resources the browser can load to improve security

B To speed up page loading by caching resources

C To style the webpage with CSS

D To manage user authentication

CSP controls resource loading to prevent attacks like cross-site scripting.

Which directive restricts where scripts can be loaded from in CSP?

A style-src

B img-src

C script-src

D connect-src

The script-src directive controls allowed sources for scripts.

In Django, which method is commonly used to add CSP headers?

A Writing CSP in templates only

B Adding CSP in models.py

C Using Django admin panel settings

D Using middleware or django-csp package

Middleware or django-csp package is used to add CSP headers in Django.

What risk does allowing unsafe-inline scripts in CSP introduce?

A Cross-site scripting (XSS) attacks

B Slower page load times

C Broken images

D Authentication failures

Allowing unsafe-inline scripts can lead to XSS attacks.

Which of these is NOT a valid CSP directive?

A font-src

B data-src

C img-src

D media-src

There is no 'data-src' directive in CSP.

Explain how Content Security Policy helps protect a Django web application.

Think about what kinds of attacks CSP blocks and how it tells the browser what is safe.

Describe how to implement a basic Content Security Policy in a Django project.

Focus on the steps from installing a package to setting rules.

Practice

1. What is the main purpose of Content Security Policy (CSP) in a Django application?

easy

A. To handle database migrations automatically

B. To speed up the loading time of the website

C. To control which external resources can be loaded by the browser

D. To manage user authentication and sessions

Solution

1. Step 1: Understand CSP's role in security

   CSP is designed to restrict what content the browser can load, preventing harmful scripts or resources.

2. Step 2: Identify the correct purpose among options

   Only To control which external resources can be loaded by the browser describes controlling external resource loading, which matches CSP's function.

3. Final Answer:

   To control which external resources can be loaded by the browser -> Option C

4. Quick Check:

   CSP purpose = control resource loading [OK]

Hint: CSP controls resource loading to improve security [OK]

Common Mistakes:

• Confusing CSP with performance optimization
• Thinking CSP manages user sessions
• Assuming CSP handles database tasks

2. Which of the following is the correct way to add a CSP header in a Django view?

easy

A. response.setHeader('Content-Security-Policy', "default-src 'self'")

B. response['headers']['Content-Security-Policy'] = "default-src 'self'"

C. response.set_header('Content-Security-Policy', "default-src 'self'")

D. response['Content-Security-Policy'] = "default-src 'self'"

Solution

1. Step 1: Recall Django HttpResponse header syntax

   In Django, headers are set by assigning to response['Header-Name'].

2. Step 2: Match the correct syntax

   response['Content-Security-Policy'] = "default-src 'self'" uses response['Content-Security-Policy'] = "default-src 'self'", which is correct Django syntax.

3. Final Answer:

   response['Content-Security-Policy'] = "default-src 'self'" -> Option D

4. Quick Check:

   Django header set = response['Header'] = value [OK]

Hint: Use response['Header-Name'] = value to set headers in Django [OK]

Common Mistakes:

• Using JavaScript or Flask header syntax in Django
• Calling non-existent methods like setHeader
• Trying to set headers via response.headers dictionary

3. Given this Django middleware snippet, what CSP header will be sent in the response?

class CSPMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        response = self.get_response(request)
        response['Content-Security-Policy'] = "script-src 'self' https://cdn.example.com"
        return response

medium

A. Content-Security-Policy: default-src 'self'

B. Content-Security-Policy: script-src 'self' https://cdn.example.com

C. No Content-Security-Policy header is set

D. Content-Security-Policy: script-src 'none'

Solution

1. Step 1: Analyze the middleware code

   The middleware sets response['Content-Security-Policy'] to "script-src 'self' https://cdn.example.com" before returning the response.

2. Step 2: Determine the header sent

   The header sent will exactly match the assigned string in the middleware.

3. Final Answer:

   Content-Security-Policy: script-src 'self' https://cdn.example.com -> Option B

4. Quick Check:

   Middleware sets CSP header = script-src 'self' https://cdn.example.com [OK]

Hint: Middleware sets header exactly as assigned before returning response [OK]

Common Mistakes:

• Assuming default-src is set instead of script-src
• Thinking header is not set because of missing return
• Confusing middleware with view-level headers

4. You added this CSP header in Django but your inline scripts stopped working:

response['Content-Security-Policy'] = "default-src 'self'"

What is the likely cause and fix?

medium

A. Inline scripts blocked; add 'unsafe-inline' to script-src directive

B. Header syntax error; remove quotes around 'self'

C. Missing HTTPS; change 'self' to https://self

D. No fix needed; inline scripts should work by default

Solution

1. Step 1: Understand CSP default-src effect on scripts

   default-src 'self' blocks inline scripts by default because inline scripts are unsafe.

2. Step 2: Fix by allowing inline scripts explicitly

   Adding 'unsafe-inline' to script-src directive allows inline scripts to run.

3. Final Answer:

   Inline scripts blocked; add 'unsafe-inline' to script-src directive -> Option A

4. Quick Check:

   Inline scripts need 'unsafe-inline' in CSP [OK]

Hint: Add 'unsafe-inline' to allow inline scripts in CSP [OK]

Common Mistakes:

• Removing quotes around 'self' breaks CSP syntax
• Changing 'self' to https://self is invalid
• Assuming inline scripts work without explicit permission

5. You want to allow images from your own site and from https://images.example.com but block all other sources. Which CSP header directive is correct in Django?

hard

A. response['Content-Security-Policy'] = "img-src 'self' https://images.example.com; default-src 'none'"

B. response['Content-Security-Policy'] = "default-src 'self' https://images.example.com"

C. response['Content-Security-Policy'] = "img-src *; default-src 'self'"

D. response['Content-Security-Policy'] = "img-src 'none'; default-src https://images.example.com"

Solution

1. Step 1: Identify directives to allow images only from specific sources

   img-src directive controls image sources; 'self' allows own site, plus https://images.example.com.

2. Step 2: Block all other sources by setting default-src to 'none'

   default-src 'none' blocks everything else not explicitly allowed.

3. Final Answer:

   response['Content-Security-Policy'] = "img-src 'self' https://images.example.com; default-src 'none'" -> Option A

4. Quick Check:

   Allow images from self and example.com, block others [OK]

Hint: Use img-src for images and default-src 'none' to block others [OK]

Common Mistakes:

• Using default-src for images allows too many sources
• Using img-src * allows all images, not secure
• Setting img-src 'none' blocks all images