Rate Limiting is Enabled in Azure Front Door WAF

Overview

Azure Front Door Web Application Firewall (WAF) supports rate limiting through custom rules that restrict the number of requests clients can make within a specified time window across the global edge network. Rate limiting is a critical defense mechanism that protects applications from abuse by throttling clients that exceed defined request thresholds before traffic reaches origin servers.

Without rate limiting configured, threat actors can execute brute force attacks, credential stuffing attacks, API abuse, and application-layer denial of service attacks that flood endpoints with requests to exhaust server capacity.

Rate limiting rules use the RateLimitRule rule type and allow administrators to define thresholds based on request count per minute, with the ability to group requests by client IP address. When a client exceeds the configured threshold, the WAF can block subsequent requests, log the violation, issue a CAPTCHA challenge, or redirect to a custom page.

This check identifies Azure Front Door WAF policies that are attached to an Azure Front Door and verifies that at least one rate limiting rule is configured and enabled.

Remediation

• Azure Web Application Firewall on Azure Front Door
• Web Application Firewall custom rules for Azure Front Door
• Rate limiting for Azure Front Door WAF
• Tutorial: Create a Web Application Firewall policy on Azure Front Door

Run it

The check runs as part of the whole assessment, with the ZeroTrustAssessment module installed:

Install-Module ZeroTrustAssessment -Scope CurrentUser
Connect-Maester
Invoke-Maester -Pack ZTA -SkipBuiltIn

Leave out -SkipBuiltIn to run Maester’s own checks in the same run.

About this check

Severity	High
Effort to fix	Medium
Impact on users	Low
Pillar	Network
Category	Azure Network Security
Product	Azure
Feature	Network security
Area	Infrastructure hardening
ATT&CK	T1110 Brute Force, T1499.003 Application Exhaustion Flood
Licence	Azure_WAF
Tenant	Workforce

Product, feature, area and ATT&CK are Maester’s: the assessment does not record them, so Maester keeps them in the pack’s taxonomy.json.

A Microsoft check, part of the Zero Trust Assessment pack. Text from ZeroTrustAssessment 3.1.0, © Microsoft, MIT licence.