Security header validation in Postman - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of security headers in HTTP responses?

Security headers help protect web applications by instructing browsers how to handle content securely, reducing risks like cross-site scripting and clickjacking.

beginner

Name three common security headers you should validate in API testing.

Common security headers include Content-Security-Policy, X-Frame-Options, and Strict-Transport-Security.

intermediate

How can you validate security headers using Postman tests?

In Postman, you write test scripts that check if the response headers contain expected security headers with correct values using pm.response.headers.get().

beginner

What does the Strict-Transport-Security header do?

It tells browsers to only connect to the site using HTTPS for a specified time, preventing insecure HTTP connections.

intermediate

Why is it important to check the X-Content-Type-Options header?

This header prevents browsers from MIME-sniffing a response away from the declared content-type, reducing the risk of executing malicious files.

Which security header prevents your site from being embedded in iframes on other sites?

A X-Frame-Options

B Content-Security-Policy

C Strict-Transport-Security

D X-Content-Type-Options

X-Frame-Options controls whether your site can be displayed in frames or iframes, protecting against clickjacking.

In Postman, which method retrieves a response header value for validation?

A pm.response.body.get()

B pm.response.headers.get()

C pm.request.headers.get()

D pm.test.headers.get()

pm.response.headers.get() fetches the value of a specific header from the response.

What does the Content-Security-Policy header help prevent?

A Server crashes

B Slow network connections

C Password leaks

D Cross-site scripting attacks

Content-Security-Policy restricts sources of content, helping prevent cross-site scripting (XSS) attacks.

Which header enforces HTTPS connections by browsers?

A Strict-Transport-Security

B X-Frame-Options

C Content-Security-Policy

D X-Content-Type-Options

Strict-Transport-Security tells browsers to use HTTPS only for a set time period.

Why should you validate security headers in API responses?

A To improve API response speed

B To check API data format

C To ensure the API is secure against common web attacks

D To verify API authentication tokens

Validating security headers helps confirm the API applies protections against web security threats.

Explain how you would write a Postman test to check for the presence and correct value of the X-Frame-Options header.

Think about how to get header values and assert them in Postman test scripts.

Describe why security headers are important in web applications and what risks they help reduce.

Consider common web vulnerabilities and how headers can protect against them.

Practice

1. Which HTTP header is commonly used to prevent clickjacking attacks by controlling if a page can be displayed in a frame or iframe?

easy

A. Strict-Transport-Security

B. Content-Security-Policy

C. X-Frame-Options

D. Cache-Control

Solution

1. Step 1: Understand clickjacking protection

   Clickjacking is prevented by restricting framing of pages.

2. Step 2: Identify the header for frame control

   The X-Frame-Options header controls if a page can be framed.

3. Final Answer:

   X-Frame-Options -> Option C

4. Quick Check:

   Clickjacking protection = X-Frame-Options [OK]

Hint: Remember: Frame control = X-Frame-Options header [OK]

Common Mistakes:

• Confusing Content-Security-Policy with frame control
• Thinking Strict-Transport-Security controls framing
• Ignoring the role of X-Frame-Options

2. Which Postman test script correctly checks if the Content-Security-Policy header exists in the response?

easy

A. pm.test('CSP header present', () => pm.expect(pm.response.headers.get('Content-Security-Policy') !== null).to.be.true);

B. pm.test('CSP header present', () => pm.response.headers.has('content-security-policy') === false);

C. pm.test('CSP header present', () => pm.response.headers.get('Content-Security-Policy') === undefined);

D. pm.test('CSP header present', () => pm.response.headers.has('Content-Security-Policy'));

Solution

1. Step 1: Understand Postman header methods

   pm.response.headers.get() returns the header value or null if missing.

2. Step 2: Check for header existence correctly

   Checking if the value is not null confirms header presence.

3. Final Answer:

   pm.test('CSP header present', () => pm.expect(pm.response.headers.get('Content-Security-Policy') !== null).to.be.true); -> Option A

4. Quick Check:

   Header exists if get() !== null [OK]

Hint: Use get() !== null to check header presence [OK]

Common Mistakes:

• Using headers.has() which returns boolean but not tested properly
• Checking for undefined instead of null
• Negating the condition incorrectly

3. Given this Postman test code, what will be the test result if the response header X-Content-Type-Options is missing?

pm.test('X-Content-Type-Options header is set', () => {
  pm.response.to.have.header('X-Content-Type-Options');
});

medium

A. Test passes because header check is optional

B. Test passes but logs a warning

C. Test throws a syntax error

D. Test fails because header is missing

Solution

1. Step 1: Understand the assertion used

   pm.response.to.have.header() asserts the header must exist.

2. Step 2: Analyze missing header effect

   If the header is missing, the assertion fails and test fails.

3. Final Answer:

   Test fails because header is missing -> Option D

4. Quick Check:

   Missing required header = test failure [OK]

Hint: Required header missing causes test failure [OK]

Common Mistakes:

• Assuming test passes if header is missing
• Confusing syntax error with assertion failure
• Thinking warnings are logged instead of failure

4. Identify the error in this Postman test script that checks if the Strict-Transport-Security header includes max-age=31536000:

pm.test('HSTS max-age check', () => {
  pm.expect(pm.response.headers.get('Strict-Transport-Security')).to.include('max-age=31536000');
});

medium

A. Not checking if header exists before calling get()

B. Using to.include instead of to.have.string

C. Incorrect header name casing

D. Missing semicolon after pm.test

Solution

1. Step 1: Understand get() behavior when header missing

   If header is missing, get() returns null, causing error on to.include.

2. Step 2: Identify missing existence check

   Test should first check header exists before checking content.

3. Final Answer:

   Not checking if header exists before calling get() -> Option A

4. Quick Check:

   Check header presence before content check [OK]

Hint: Always verify header exists before content assertions [OK]

Common Mistakes:

• Assuming get() never returns null
• Ignoring null causing test errors
• Focusing on casing or semicolons instead

5. You want to write a Postman test to ensure the Content-Security-Policy header disallows inline scripts by including script-src 'self'. Which test script correctly validates this?

hard

A. pm.test('CSP disallows inline scripts', () => {
pm.expect(pm.response.headers.get('Content-Security-Policy')).to.equal("script-src 'self'");
});

B. pm.test('CSP disallows inline scripts', () => {
const csp = pm.response.headers.get('Content-Security-Policy');
pm.expect(csp).to.include("script-src 'self'");
});

C. pm.test('CSP disallows inline scripts', () => {
pm.expect(pm.response.headers.has('Content-Security-Policy')).to.be.true;
});

D. pm.test('CSP disallows inline scripts', () => {
pm.expect(pm.response.headers.get('Content-Security-Policy')).to.include('unsafe-inline');
});

Solution

1. Step 1: Understand CSP header content

   The header can contain multiple directives; we check if it includes script-src 'self'.

2. Step 2: Validate correct assertion method

   Using to.include checks if the string contains the directive, allowing other parts.

3. Final Answer:

   pm.test('CSP disallows inline scripts', () => { const csp = pm.response.headers.get('Content-Security-Policy'); pm.expect(csp).to.include("script-src 'self'"); }); -> Option B

4. Quick Check:

   Use include() to check partial CSP directive [OK]

Hint: Use include() to check CSP directives inside header string [OK]

Common Mistakes:

• Using to.equal which requires exact match
• Only checking header presence without content
• Checking for 'unsafe-inline' which allows inline scripts