Configuring a WAF basic rule set

With Terraform, you can quickly create a cloud infrastructure in Yandex Cloud and manage it using configuration files. These files store the infrastructure description written in HashiCorp Configuration Language (HCL). If you change the configuration files, Terraform automatically detects which part of your configuration is already deployed, and what should be added or removed.

Terraform is distributed under the Business Source License. The Yandex Cloud provider for Terraform is distributed under the MPL-2.0 license.

For more information about the provider resources, see the documentation on the Terraform website or mirror website.

If you don't have Terraform, install it and configure the Yandex Cloud provider.

You can dynamically activate all the basic set rules if their paranoia level is not higher than specified in the user variable. You can manually edit the parameters of dynamically configured rules. For example, you can turn a rule into a blocking one and activate a rule with paranoia level higher than specified in the variable.

1. Open the Terraform configuration file and edit the fragment with yandex_sws_waf_profile description: add either a section named rule with a security rule or a section named dynamic "rule" with dynamically configured rules.

   # In the basic set, rules of this paranoia level and below will be active
   locals {
     waf_paranoia_level = 1
   }
   
   # OWASP Core Rule Set data source
   data "yandex_sws_waf_rule_set_descriptor" "owasp4" {
     name    = "OWASP Core Ruleset"
     version = "4.0.0"
   }
   
   # WAF profile
   resource "yandex_sws_waf_profile" "default" {
     name = "<WAF_profile_name>"
   
     # Basic rule set
     core_rule_set {
       inbound_anomaly_score = 2
       paranoia_level        = local.waf_paranoia_level
       rule_set {
         name    = "OWASP Core Ruleset"
         version = "4.0.0"
       }
     }
   
     # Turning the rule into a blocking one: the request will be blocked regardless of the anomaly threshold
     rule {
       rule_id     = "owasp-crs-v4.0.0-id942330-attack-sqli"
       is_enabled  = true
       is_blocking = true
     }
   
     # Turning the rule with paranoia level 4 into an active one
     rule {
       rule_id     = "owasp-crs-v4.0.0-id920202-protocol-enforcement"
       is_enabled  = true
       is_blocking = false
     }
   
     # Activating rules from the basic set if their paranoia level is not higher than specified in the waf_paranoia_level variable
     dynamic "rule" {
       for_each = [
         for rule in data.yandex_sws_waf_rule_set_descriptor.owasp4.rules : rule
         if rule.paranoia_level <= local.waf_paranoia_level
       ]
       content {
         rule_id     = rule.value.id
         is_enabled  = true
         is_blocking = false
       }
     }
   
     analyze_request_body {
       is_enabled        = true
       size_limit        = 8
       size_limit_action = "IGNORE"
     }
   }
   

   Where:

   • dynamic "rule": Dynamic activation of rules from the basic set if their paranoia level is not higher than specified in the waf_paranoia_level variable. You can manually edit the parameters of dynamically configured rules. For example, you can turn a rule into a blocking one or activate a rule with paranoia level higher than specified in the variable.
     • rule_id: Rule ID.
     • is_enabled: Flag to enable or disable a rule.
     • is_blocking: Blocking rule flag.

   For more information about the sws_waf_profile resource parameters in Terraform, see the relevant provider documentation.

2. Create resources:

   1. In the terminal, change to the folder where you edited the configuration file.

   2. Make sure the configuration file is correct using the command:

      terraform validate
      

      If the configuration is correct, the following message is returned:

      Success! The configuration is valid.
      

   3. Run the command:

      terraform plan
      

      The terminal will display a list of resources with parameters. No changes are made at this step. If the configuration contains errors, Terraform will point them out.

   4. Apply the configuration changes:

      terraform apply
      

   5. Confirm the changes: type yes in the terminal and press Enter.

You can check the updates of your resources in the management console.