Authentication (DAST) (ULTIMATE)

WARNING: Never run an authenticated scan against a production server. Authenticated scans may perform any function that the authenticated user can, including modifying or deleting data, submitting forms, and following links. Only run an authenticated scan against a test server.

Authentication logs a user in before a DAST scan so that the analyzer can test as much of the application as possible when searching for vulnerabilities.

DAST uses a browser to authenticate the user so that the login form has the necessary JavaScript and styling required to submit the form. DAST finds the username and password fields and fills them with their respective values. The login form is submitted, and when the response returns, a series of checks verify if authentication was successful. DAST saves the credentials for reuse when crawling the target application.

If DAST fails to authenticate, the scan halts and the CI job fails.

Authentication supports single-step login forms, multi-step login forms, single sign-on, and authenticating to URLs outside of the configured target URL.

Getting started

NOTE: We recommend periodically confirming that the analyzer's authentication is still working, as this tends to break over time due to changes to the application.

To run a DAST authenticated scan:

• Read the prerequisite conditions for authentication.
• Update your target website to a landing page of an authenticated user.
• If your login form has the username, password and submit button on a single page, use the CI/CD variables to configure single-step login form authentication.
• If your login form has the username and password fields on different pages, use the CI/CD variables to configure multi-step login form authentication.
• Make sure the user isn't logged out during the scan.

Prerequisites

• You are using either the DAST proxy-based analyzer or the DAST browser-based analyzer.
• You know the URL of the login form of your application. Alternatively, you know how to navigate to the login form from the authentication URL (see clicking to navigate to the login form).
• You have the username and password of the user you would like to authenticate as during the scan.
• You know the selectors of the username and password HTML fields that DAST will use to input the respective values.
• You know the element's selector that will submit the login form when selected.
• You have thought about how you can verify whether or not authentication was successful.
• You have checked the known limitations to ensure DAST can authenticate to your application.

Available CI/CD variables

1. Available to an on-demand proxy-based DAST scan.

Update the target website

The target website, defined using the CI/CD variable DAST_WEBSITE, is the URL DAST uses to begin crawling your application.

For best crawl results on an authenticated scan, the target website should be a URL accessible only after the user is authenticated. Often, this is the URL of the page the user lands on after they're logged in.

For example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com/dashboard/welcome"
    DAST_AUTH_URL: "https://example.com/login"

Configuration for a single-step login form

A single-step login form has all login form elements on a single page. Configuration requires the CI/CD variables DAST_AUTH_URL, DAST_USERNAME, DAST_USERNAME_FIELD, DAST_PASSWORD, DAST_PASSWORD_FIELD, and DAST_SUBMIT_FIELD to be defined for the DAST job.

It is recommended to set up the URL and selectors of fields in the job definition YAML, for example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_URL: "https://example.com/login"
    DAST_USERNAME_FIELD: "css:[name=username]"
    DAST_PASSWORD_FIELD: "css:[name=password]"
    DAST_SUBMIT_FIELD: "css:button[type=submit]"

Do not define DAST_USERNAME and DAST_PASSWORD in the YAML job definition file as this could present a security risk. Instead, create them as masked CI/CD variables using the GitLab UI. See Custom CI/CI variables for more information.

Configuration for a multi-step login form

A multi-step login form has two pages. The first page has a form with the username and a next submit button. If the username is valid, a second form on the subsequent page has the password and the form submit button.

Configuration requires the CI/CD variables DAST_AUTH_URL, DAST_USERNAME, DAST_USERNAME_FIELD, DAST_FIRST_SUBMIT_FIELD, DAST_PASSWORD, DAST_PASSWORD_FIELD, and DAST_SUBMIT_FIELD to be defined for the DAST job.

It is recommended to set up the URL and selectors of fields in the job definition YAML, for example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_URL: "https://example.com/login"
    DAST_USERNAME_FIELD: "css:[name=username]"
    DAST_FIRST_SUBMIT_FIELD: "css:button[name=next]"
    DAST_PASSWORD_FIELD: "css:[name=password]"
    DAST_SUBMIT_FIELD: "css:button[type=submit]"

Do not define DAST_USERNAME and DAST_PASSWORD in the YAML job definition file as this could present a security risk. Instead, create them as masked CI/CD variables using the GitLab UI. See Custom CI/CI variables for more information.

Configuration for Single Sign-On (SSO)

If a user can log into an application, then in most cases, DAST will also be able to log in. This is the case even when an application uses Single Sign-on. Applications using SSO solutions should configure DAST authentication using the single-step or multi-step login form configuration guides.

DAST supports authentication processes where a user is redirected to an external Identity Provider's site to log in. Check the known limitations of DAST authentication to determine if your SSO authentication process is supported.

Clicking to navigate to the login form

Define DAST_BROWSER_PATH_TO_LOGIN_FORM to provide a path of elements to click on from the DAST_AUTH_URL so that DAST can access the login form. This is useful for applications that show the login form in a pop-up (modal) window or when the login form does not have a unique URL.

For example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_URL: "https://example.com/login"
    DAST_BROWSER_PATH_TO_LOGIN_FORM: "css:.navigation-menu,css:.login-menu-item"

Excluding logout URLs

If DAST crawls the logout URL while running an authenticated scan, the user will be logged out, resulting in the remainder of the scan being unauthenticated. It is therefore recommended to exclude logout URLs using the CI/CD variable DAST_EXCLUDE_URLS. DAST will not access any excluded URLs, ensuring the user remains logged in.

Provided URLs can be either absolute URLs, or regular expressions of URL paths relative to the base path of the DAST_WEBSITE. For example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com/welcome/home"
    DAST_EXCLUDE_URLS: "https://example.com/logout,/user/.*/logout"

Finding an element's selector

Selectors are used by CI/CD variables to specify the location of an element displayed on a page in a browser. Selectors have the format type:search string. DAST searches for the selector using the search string based on the type.

Find selectors with Google Chrome

Chrome DevTools element selector tool is an effective way to find a selector.

1. Open Chrome and navigate to the page where you would like to find a selector, for example, the login page for your site.
2. Open the Elements tab in Chrome DevTools with the keyboard shortcut Command + Shift + c in macOS or Ctrl + Shift + c in Windows.
3. Select the Select an element in the page to select it tool.
4. Select the field on your page that you would like to know the selector for.
5. Once the tool is active, highlight a field you wish to view the details of.
6. Once highlighted, you can see the element's details, including attributes that would make a good candidate for a selector.

In this example, the id="user_login" appears to be a good candidate. You can use this as a selector as the DAST username field by setting DAST_USERNAME_FIELD: "id:user_login".

Choose the right selector

Judicious choice of selector leads to a scan that is resilient to the application changing.

In order of preference, it is recommended to choose as selectors:

• id fields. These are generally unique on a page, and rarely change.
• name fields. These are generally unique on a page, and rarely change.
• class values specific to the field, such as the selector "css:.username" for the username class on the username field.
• Presence of field specific data attributes, such as the selector, "css:[data-username]" when the data-username field has any value on the username field.
• Multiple class hierarchy values, such as the selector "css:.login-form .username" when there are multiple elements with class username but only one nested inside the element with the class login-form.

When using selectors to locate specific fields we recommend you avoid searching on:

• Any id, name, attribute, class or value that is dynamically generated.
• Generic class names, such as column-10 and dark-grey.
• XPath searches as they are less performant than other selector searches.
• Unscoped searches, such as those beginning with css:* and xpath://*.

Verifying authentication is successful

Once DAST has submitted the login form, a verification process takes place to determine if authentication succeeded. The scan will halt with an error if authentication is unsuccessful.

Following the submission of the login form, authentication is determined to be unsuccessful when:

• The login submit HTTP response has a 400 or 500 series status code.
• Any verification check fails.
• An authentication token with a sufficiently random value is not set during the authentication process.

Verification checks

Verification checks run checks on the state of the browser once authentication is complete to determine further if authentication succeeded.

DAST will test for the absence of a login form if no verification checks are configured.

Verify based on the URL

Define DAST_AUTH_VERIFICATION_URL as the URL displayed in the browser tab once the login form is successfully submitted.

DAST will compare the verification URL to the URL in the browser after authentication. If they are not the same, authentication is unsuccessful.

For example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_VERIFICATION_URL: "https://example.com/user/welcome"

Verify based on presence of an element

Define DAST_AUTH_VERIFICATION_SELECTOR as a selector that will find one or many elements on the page displayed once the login form is successfully submitted. If no element is found, authentication is unsuccessful. Searching for the selector on the page displayed when login fails should return no elements.

For example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_VERIFICATION_SELECTOR: "css:.welcome-user"

Verify based on absence of a login form

Define DAST_AUTH_VERIFICATION_LOGIN_FORM as "true" to indicate that DAST should search for the login form on the page displayed once the login form is successfully submitted. If a login form is still present after logging in, authentication is unsuccessful.

For example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_VERIFICATION_LOGIN_FORM: "true"

Authentication tokens

DAST records authentication tokens set during the authentication process. Authentication tokens are loaded into new browsers when DAST opens them so the user can remain logged in throughout the scan.

To record tokens, DAST takes a snapshot of cookies, local storage, and session storage values set by the application before the authentication process. DAST does the same after authentication and uses the difference to determine which were created by the authentication process.

DAST considers cookies, local storage and session storage values set with sufficiently "random" values to be authentication tokens. For example, sessionID=HVxzpS8GzMlPAc2e39uyIVzwACIuGe0H would be viewed as an authentication token, while ab_testing_group=A1 would not.

The CI/CD variable DAST_AUTH_COOKIES can be used to specify the names of authentication cookies and bypass the randomness check used by DAST. Not only can this make the authentication process more robust, but it can also increase vulnerability check accuracy for checks that inspect authentication tokens.

For example:

include:
  - template: DAST.gitlab-ci.yml

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_COOKIES: "sessionID,refreshToken"

Known limitations

• DAST cannot bypass a CAPTCHA if the authentication flow includes one. Please turn these off in the testing environment for the application being scanned.
• DAST cannot handle multi-factor authentication like one-time passwords (OTP) by using SMS, biometrics, or authenticator apps. Please turn these off in the testing environment for the application being scanned.
• DAST cannot authenticate to applications that do not set an authentication token during login.
• DAST cannot authenticate to applications that require more than two inputs to be filled out. Two inputs must be supplied, username and password.

Troubleshooting

The logs provide insight into what DAST is doing and expecting during the authentication process. For more detailed information, configure the authentication report.

For more information about particular error messages or situations see known problems.

The browser-based analyzer is used to authenticate the user. For advanced troubleshooting, see browser-based troubleshooting.

Read the logs

The console output of the DAST CI/CD job shows information about the authentication process using the AUTH log module. For example, the following log shows failed authentication for a multi-step login form. Authentication failed because a home page should be displayed after login. Instead, the login form was still present.

2022-11-16T13:43:02.000 INF AUTH  attempting to authenticate
2022-11-16T13:43:02.000 INF AUTH  loading login page LoginURL=https://example.com/login
2022-11-16T13:43:10.000 INF AUTH  multi-step authentication detected
2022-11-16T13:43:15.000 INF AUTH  verifying if user submit was successful true_when="HTTP status code < 400"
2022-11-16T13:43:15.000 INF AUTH  requirement is satisfied, no login HTTP message detected want="HTTP status code < 400"
2022-11-16T13:43:20.000 INF AUTH  verifying if login attempt was successful true_when="HTTP status code < 400 and has authentication token and no login form found (no element found when searching using selector css:[id=email] or css:[id=password] or css:[id=submit])"
2022-11-24T14:43:20.000 INF AUTH  requirement is satisfied, HTTP login request returned status code 200 url=https://example.com/user/login?error=invalid%20credentials want="HTTP status code < 400"
2022-11-16T13:43:21.000 INF AUTH  requirement is unsatisfied, login form was found want="no login form found (no element found when searching using selector css:[id=email] or css:[id=password] or css:[id=submit])"
2022-11-16T13:43:21.000 INF AUTH  login attempt failed error="authentication failed: failed to authenticate user"

Configure the authentication report

An authentication report can be saved as a CI/CD job artifact to assist with understanding the cause of an authentication failure.

The report contains steps during the login process, HTTP requests and responses, the Document Object Model (DOM) and screenshots.

An example configuration where the authentication debug report is exported may look like the following:

dast:
  variables:
    DAST_WEBSITE: "https://example.com"
    DAST_AUTH_REPORT: "true"
  artifacts:
    paths: [gl-dast-debug-auth-report.html]
    when: always

Known problems

Login form not found

DAST failed to find a login form when loading the login page, often because the authentication URL could not be loaded. The log reports a fatal error such as:

2022-12-07T12:44:02.838 INF AUTH  loading login page LoginURL=[authentication URL]
2022-12-07T12:44:11.119 FTL MAIN  authentication failed: login form not found

Suggested actions:

• Generate the authentication report to inspect HTTP response.
• Check the target application authentication is deployed and running.
• Check the DAST_AUTH_URL is correct.
• Check the GitLab Runner can access the DAST_AUTH_URL.
• Check the DAST_BROWSER_PATH_TO_LOGIN_FORM is valid if used.

Scan doesn't crawl authenticated pages

If DAST captures the wrong authentication tokens during the authentication process then the scan can't crawl authenticated pages. Names of cookies and storage authentication tokens are written to the log. For example:

2022-11-24T14:42:31.492 INF AUTH  authentication token cookies names=["sessionID"]
2022-11-24T14:42:31.492 INF AUTH  authentication token storage events keys=["token"]

Suggested actions:

• Generate the authentication report and look at the screenshot from the Login submit to verify that the login worked as expected.
• Verify the logged authentication tokens are those used by your application.
• If using cookies to store authentication tokens, set the names of the authentication token cookies using DAST_AUTH_COOKIES.

Unable to find elements with selector

DAST failed to find the username, password, first submit button, or submit button elements. The log reports a fatal error such as:

2022-12-07T13:14:11.545 FTL MAIN  authentication failed: unable to find elements with selector: css:#username

Suggested actions:

• Generate the authentication report to use the screenshot from the Login page to verify that the page loaded correctly.
• Load the login page in a browser and verify the selectors configured in DAST_USERNAME_FIELD, DAST_PASSWORD_FIELD, DAST_FIRST_SUBMIT_FIELD, and DAST_SUBMIT_FIELD are correct.

Failed to authenticate user

DAST failed to authenticate due to a failed login verification check. The log reports a fatal error such as:

2022-12-07T06:39:49.483 INF AUTH  verifying if login attempt was successful true_when="HTTP status code < 400 and has authentication token and no login form found (no element found when searching using selector css:[name=username] or css:[name=password] or css:button[type=\"submit\"])"
2022-12-07T06:39:49.484 INF AUTH  requirement is satisfied, HTTP login request returned status code 303 url=http://auth-manual:8090/login want="HTTP status code < 400"
2022-12-07T06:39:49.513 INF AUTH  requirement is unsatisfied, login form was found want="no login form found (no element found when searching using selector css:[name=username] or css:[name=password] or css:button[type=\"submit\"])"
2022-12-07T06:39:49.589 INF AUTH  login attempt failed error="authentication failed: failed to authenticate user"
2022-12-07T06:39:53.626 FTL MAIN  authentication failed: failed to authenticate user

Suggested actions:

• Look in the log for the requirement is unsatisfied. Respond to the appropriate error.

Requirement unsatisfied, login form was found

Applications typically display a dashboard when the user logs in and the login form with an error message when the username or password is incorrect.

This error occurs when DAST detects the login form on the page displayed after authenticating the user, indicating that the login attempt failed.

2022-12-07T06:39:49.513 INF AUTH  requirement is unsatisfied, login form was found want="no login form found (no element found when searching using selector css:[name=username] or css:[name=password] or css:button[type=\"submit\"])"

Suggested actions:

• Verify that the username and password/authentication credentials used are correct.
• Generate the authentication report and verify the Request for the Login submit is correct.
• It's possible that the authentication report Login submit request and response are empty. This occurs when there is no request that would result in a full page reload, such as a request made when submitting a HTML form. This occurs when using websockets or AJAX to submit the login form.
• If the page displayed following user authentication genuinely has elements matching the login form selectors, configure DAST_AUTH_VERIFICATION_URL or DAST_AUTH_VERIFICATION_SELECTOR to use an alternate method of verifying the login attempt.

Requirement unsatisfied, selector returned no results

DAST cannot find an element matching the selector provided in DAST_AUTH_VERIFICATION_SELECTOR on the page displayed following user login.

2022-12-07T06:39:33.239 INF AUTH  requirement is unsatisfied, searching DOM using selector returned no results want="has element css:[name=welcome]"

Suggested actions:

• Generate the authentication report and look at the screenshot from the Login submit to verify that the expected page is displayed.
• Ensure the DAST_AUTH_VERIFICATION_SELECTOR selector is correct.

Requirement unsatisfied, browser not at URL

DAST detected that the page displayed following user login has a URL different to what was expected according to DAST_AUTH_VERIFICATION_URL.

2022-12-07T11:28:00.241 INF AUTH  requirement is unsatisfied, browser is not at URL browser_url="https://example.com/home" want="is at url https://example.com/user/dashboard"

Suggested actions:

• Generate the authentication report and look at the screenshot from the Login submit to verify that the expected page is displayed.
• Ensure the DAST_AUTH_VERIFICATION_URL is correct.

Requirement unsatisfied, HTTP login request status code

The HTTP response when loading the login form or submitting the form had a status code of 400 (client error) or 500 (server error).

2022-12-07T06:39:53.626 INF AUTH  requirement is unsatisfied, HTTP login request returned status code 502 url="https://example.com/user/login" want="HTTP status code < 400"

• Verify that the username and password/authentication credentials used are correct.
• Generate the authentication report and verify the Request for the Login submit is correct.
• Verify the target application works as expected.

Requirement unsatisfied, no authentication token

DAST could not detect an authentication token created during the authentication process.

2022-12-07T11:25:29.010 INF AUTH  authentication token cookies names=[]
2022-12-07T11:25:29.010 INF AUTH  authentication token storage events keys=[]
2022-12-07T11:25:29.010 INF AUTH  requirement is unsatisfied, no basic authentication, cookie or storage event authentication token detected want="has authentication token"

Suggestion actions:

• Generate the authentication report and look at the screenshot from the Login submit to verify that the login worked as expected.
• Using the browser's developer tools, investigate the cookies and local/session storage objects created while logging in. Ensure there is an authentication token created with sufficiently random value.
• If using cookies to store authentication tokens, set the names of the authentication token cookies using DAST_AUTH_COOKIES.