Under Attack mode

Cloudflare's Under Attack mode performs additional security checks to help mitigate layer 7 DDoS attacks. Validated users access your website and suspicious traffic is blocked. It is designed to be used as one of the last resorts when a zone is under attack (and will temporarily pause access to your site and impact your site analytics).

When enabled, visitors receive an interstitial page.

Turn on Under Attack mode

Under Attack mode is turned off by default for your zone.

Globally

To put your entire zone in Under Attack mode:

1. Log in to the Cloudflare dashboard ↗.
2. Select your account and zone.
3. In the zone overview page, turn on Under Attack Mode in the Quick Actions sidebar.

Selectively

To enable Under Attack mode for specific pages or sections of your site, use a configuration rule to adjust the Security Level.

When incoming requests match

• Field: URI Path
• Operator: starts with
• Value: /admin

If you are using the Expression Editor, enter the following expression:
(starts_with(http.request.uri.path, "/admin"))

Then the settings are

1. For I'm Under Attack, select Add.
2. Switch the toggle to On.

To turn it on for specific ASNs (hosts/ISPs that own IP addresses), countries, or IP ranges, use IP Access Rules.

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Preview Under Attack mode

To preview what Under Attack mode looks like for your visitors:

1. Log into the Cloudflare dashboard ↗.
2. Select your account.
3. Go to Manage Account > Configurations.
4. Go to Custom Pages.
5. For Managed Challenge / I'm Under Attack Mode™, select Custom Pages > View default.

The Checking your browser before accessing... challenge determines whether to block or allow a visitor within five seconds. After passing the challenge, the visitor does not observe another challenge until the duration configured in Challenge Passage.

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Potential issues

Since the Under Attack mode requires your browser to support JavaScript to display and pass the interstitial page, it is expected to observe impact on third party analytics tools.