Application Gateway WAF should be in Prevention mode

High Azure General appgw-waf-2

Applies to

Microsoft.Network/applicationGateways

What CGPulse checks

A resource passes this rule when webApplicationFirewall.firewallMode must equal Prevention. Anything else is reported as a finding with the evaluated property value attached as evidence.

How to fix it

Switch WAF to Prevention mode to actively block threats after verifying no false positives. In Azure Portal: WAF policy > switch Mode to Prevention. See: https://learn.microsoft.com/en-us/azure/web-application-firewall/ag/ag-overview#waf-modes

Careful: Prevention mode actively blocks requests matching WAF rules. Start with Detection mode first to verify no false positives

CLI

az network application-gateway waf-policy policy-setting update -g "{rg}" --policy-name "{name}-waf-policy" --mode Prevention --state Enabled

Terraform

resource "azurerm_web_application_firewall_policy" "{name}" {
  name                = "{name}-waf-policy"
  resource_group_name = "{rg}"
  location            = var.location
  policy_settings {
    enabled = true
    mode    = "Prevention"
  }
}

Compliance frameworks

Cloud Security BaselineNS-6

Vendor documentation

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