All Products
Search
Document Center

Web Application Firewall:Configure data leakage prevention rules to prevent sensitive information leakage

Last Updated:Nov 21, 2025

After you add your website to Web Application Firewall (WAF), you can configure data leakage prevention rules. These rules filter sensitive information, such as ID card numbers, phone numbers, bank card numbers, and sensitive words, from server responses. WAF can mask the sensitive information or return a default error response page. This topic describes how to create a data leakage prevention template and add protection rules to the template.

Limits

  • Protected objects in cloud native mode (ALB, MSE, FC) do not support this feature.

Prerequisites

Step 1: Create a data leakage prevention template

Data leakage prevention rules do not have a default protection template. To enable data leakage prevention, you must create a new protection template and add rules to it.

  1. Log on to the WAF 3.0 console. In the top navigation bar, select the resource group and region of the WAF instance. You can select Chinese Mainland or Outside Chinese Mainland.

  2. In the left-side navigation pane, choose Protection Configuration > Core Web Protection.

  3. In the Data Leakage Prevention section of the Core Web Protection page, click Create Template.

  4. In the Create Template - Data Leakage Prevention panel, configure the parameters for the template and click OK.

    Configuration Item

    Description

    Template Name

    Enter a name for the template.

    The name of the template must be 1 to 255 characters in length and can contain letters, digits, periods (.), underscores (_), and hyphens (-).

    Rule Configuration

    You can click Create Rule to create a data leakage prevention rule for the current template. You can also skip this setting and create a rule for the template after the template is created. For more information, see Step 2: Add a data leakage prevention rule to a template.

    Apply To

    From the added protected objects and object groups, select the Protected Objects and Protected Object Groups to which you want to apply the template.

    A protected object or object group can be associated with only one template in the current protection module. For more information about how to add protected objects and object groups, see Configure protected objects and protected object groups.

    By default, a newly created protection template is enabled. You can perform the following operations on the template in the template list:

    • View the numbers of protected objects and protected object groups that are associated with the template in the Protected Object/Group column.

    • Turn on or turn off the switch in the Status column to enable or disable the template.

    • Click Create Rule in the Actions column to create a protection rule for the template.

    • Click Edit, Delete, or Copy in the Actions column to manage the template.

    • Click the 展开图标 icon to the left of the template name to view the protection rules in the template.

Step 2: Add a data leakage prevention rule to a template

A data leakage prevention template takes effect only after you add protection rules to it. If you added rules when you created the template, you can skip this step.

  1. Log on to the WAF 3.0 console. In the top navigation bar, select the resource group and region of the WAF instance. You can select Chinese Mainland or Outside Chinese Mainland.

  2. In the left-side navigation pane, choose Protection Configuration > Core Web Protection.

  3. In the Data Leakage Prevention section, find the protection template to which you want to add a rule, expand the template, and then click Create Rule in the Actions column.

  4. In the Create Rule dialog box, configure the parameters for the rule and click OK.

    Configuration Item

    Description

    Rule Name

    Enter a name for the rule.

    The name of the rule can contain letters, digits, periods (.), underscores (_), and hyphens (-).

    Match Condition

    Defines the type of sensitive information to detect in the response. Valid values:

    • Status Code: 400, 401, 402, 403, 404, 500, 501, 502, 503, 504, 405~499, and 505~599.

    • Sensitive Info: ID Card Numbers, Credit Card Number, Mobile Phone Number, and Default Sensitive Words.

      Important

      The data leakage prevention feature currently supports only data formats used in the Chinese mainland, such as ID card numbers, phone numbers, and bank card numbers. It does not support data formats from outside the Chinese mainland.

    You can specify one or more types under the Response Code and Sensitive Information categories.

    If you select AND, you can also specify a URL to detect sensitive information only on that page.

    Action

    Defines the action to take when sensitive information is detected in a response.

    • When the match condition is Status Code, the following actions are supported:

      • Monitor: Records a log entry when a request hits the rule but does not block the request.

      • Block: Blocks the request that hits the rule and returns a block page to the client.

    • When the match condition is Sensitive Info, the following actions are supported:

      • Monitor: Records a log entry when a request hits the rule but does not block the request.

      • Mask: Does not block the request that hits the rule but replaces parts of the sensitive information with asterisks (*).

    By default, a newly created protection rule is enabled. You can perform the following operations on the rule in the rule list:

    • View the rule ID and action in the Rule ID and Action columns.

    • Turn on or turn off the switch in the Status column to enable or disable the rule.

    • Click Edit or Delete in the Actions column to modify or delete the rule.

What to do next

You can view the protection details for the rules on the Data Leakage Prevention tab of the Security Reports page. For more information, see Security reports.

References