Arkose Protect

Arkose Protect is used on and is not supported for self-managed GitLab instances. The following documents the internal requirements for maintaining Arkose Protect on While this feature is theoretically usable in self-managed instances, it is not recommended at the moment.

GitLab integrates Arkose Protect to guard against credential stuffing and bots in the sign-in form. GitLab will trigger Arkose Protect if the user:

  • Has never signed in before.
  • Has failed to sign in twice in a row.
  • Has not signed in during the past three months.

How does it work?

If Arkose Protect determines that the user is suspicious, it presents an interactive challenge below the Sign in button. The challenge needs to be completed to proceed with the sign-in attempt. If Arkose Protect trusts the user, the challenge runs in transparent mode, meaning that the user doesn’t need to take any additional action and can sign in as usual.

How do we treat malicious sign-in attempts?

Users are not denied access if Arkose Protect considers they are malicious. However, their risk score is exposed in the admin console so that we can make more informed decisions when it comes to manually blocking users. When we decide to block a user, feedback is sent to ArkoseLabs to improve their risk prediction model.

Enabling the arkose_labs_prevent_login feature flag results in sessions with a High risk score being denied access. So far, we have kept this feature flag disabled to evaluate Arkose Protect’s predictions and to make sure we are not preventing legitimate users from signing in.

That said, we have seen that interactive challenges are effective in preventing some malicious sign-in attempts as not completing them prevents attackers from moving on to the next sign-in step.


To enable Arkose Protect:

  1. License ArkoseLabs.
  2. Get the public and private API keys from the ArkoseLabs Portal.
  3. Enable the ArkoseLabs login challenge. Run the following commands in the Rails console, replacing <your_public_api_key> and <your_private_api_key> with your own API keys.

    ApplicationSetting.current.update(arkose_labs_public_api_key: '<your_public_api_key>')
    ApplicationSetting.current.update(arkose_labs_private_api_key: '<your_private_api_key>')
  4. Optional. To prevent high risk sessions from signing, enable the arkose_labs_prevent_login feature flag. Run the following command in the Rails console:


QA tests caveat

Several GitLab QA test suites need to sign in to the app to test its features. This can conflict with Arkose Protect as it would identify QA users as being malicious because they are being run with a headless browser. To work around this, ArkoseLabs has allowlisted the unique token that serves as QA session’s User Agent. While this doesn’t guarantee that the session won’t be flagged as malicious, Arkose’s API returns a specific telltale when we verify the sign in attempt’s token. We are leveraging this telltale to bypass the verification step entirely so that the test suite doesn’t fail. This bypass is done in the UserVerificationService class.

Feedback Job

To help Arkose improve their protection service, we created a daily background job to send them the list of blocked users by us. This job is performed by the Arkose::BlockedUsersReportWorker class.