waf

AWS WAF

Overview

Domain expertise for configuring AWS WAF, the web application firewall that filters HTTP and HTTPS
traffic to CloudFront distributions, Application Load Balancers, API Gateway REST APIs, and AppSync
GraphQL APIs. Covers web ACL creation and association, AWS Managed Rules, rate-based rules, match
rules (IP set and geographic), Bot Control and the signal-forwarding workflows built on top of it,
Fraud Control for logins and signups, AI and LLM crawler management, and the logging that every
tuning workflow depends on.

This skill is a router. Each customer task maps to a procedure file under references/. Read the
matching reference in full before acting, then follow its constraints and steps. The reference
files are self-contained: each carries its own decision tables, constraints, procedure, and
troubleshooting.

Execute commands using the AWS MCP server when connected (sandboxed execution, audit logging,
observability). Fall back to the AWS CLI otherwise. A web ACL's scope is fixed at creation: a
CloudFront web ACL must be created in us-east-1 with CLOUDFRONT scope, while a regional web ACL
(Application Load Balancer, API Gateway, AppSync) is created in the resource's Region with
REGIONAL scope.

Which WAF task do you need?

Routing notes

• Logging comes before tuning. Every Count-mode tuning workflow assumes logging and request
  sampling are on. If the customer has not set up logging, run that reference first; otherwise
  Count-mode tuning has nothing to read.
• Web ACL scope is fixed at creation. A CloudFront web ACL is CLOUDFRONT scope in
  us-east-1; a regional resource needs a REGIONAL web ACL in its own Region. Scope cannot be
  changed later, so the creating reference settles it before anything is built.
• Bot Control is a chain, not one task. Protecting against bots is the on-ramp (turn on, choose
  Common vs Targeted, observe). Turning labels into a confidence signal, forwarding that signal,
  and deciding what the application does with it are three separate references that build on it in
  that order. The header-stripping reference is the mandatory safety companion whenever a signal is
  forwarded to the origin.
• Common vs Targeted is not a soft choice. Common only catches self-identifying bots and
  known-bad IPs. For login, checkout, or any high-value endpoint facing evasive bots, Targeted with
  the application integration SDK is required. The bots reference pushes Targeted for real bot
  threats rather than presenting it as optional.
• Rate limiting vs Fraud Control. Rate-based rules blunt volumetric HTTP floods. Credential
  stuffing and fake-account creation are account-based abuse that rate limiting misses; those go to
  the Fraud Control reference (ATP and ACFP), not the rate-based reference.
• Forwarded headers need the strip rule. Any time the customer forwards a signal or the client
  IP to the origin in x-amzn-waf-* headers, the inbound-header-stripping reference is required to
  prevent spoofing. The confidence-signal, interpolation, and client-IP references all point at it.
• What lives in other skills. L3/L4 DDoS protection and Shield cost-protection credits are the
  shieldadvanced skill. Multi-account WAF rollout is the firewallmanager skill. CloudFront and
  Application Load Balancer configuration are their own skills. This skill builds the WAF rules; it
  does not configure the resources it protects.

Security Considerations

AWS WAF is itself a security control, so misconfiguration directly weakens an application's defenses.
Apply these across every reference:

• Least-privilege IAM. You MUST grant only the specific wafv2: actions a task needs (for
  example wafv2:CreateWebACL, wafv2:GetWebACL, wafv2:UpdateWebACL, wafv2:AssociateWebACL,
  wafv2:PutLoggingConfiguration) rather than wafv2:* or the AWSWAFFullAccess managed policy.
• Ephemeral credentials. You MUST use IAM roles with temporary credentials (such as an EC2
  instance profile, SSO session, or aws sts assume-role) rather than long-lived IAM user access
  keys when running these WAF CLI commands.
• Monitor configuration changes. You SHOULD enable AWS CloudTrail on wafv2 management events
  and set CloudWatch alarms on critical web ACL configuration changes (such as DeleteWebACL and
  UpdateWebACL rule removals) and on the web ACL's BlockedRequests and CountedRequests
  metrics, so rule changes and sudden spikes in blocked or counted traffic are detected.
• Misconfiguration opens access. A web ACL that is created but never associated, or one whose
  default action is left at Allow with no enforcing rules, filters nothing. You MUST confirm the
  web ACL is associated and that its posture matches the intended default (block vs allow) before
  reporting setup complete.
• Protect log destinations. Logs can capture credentials and session data. You MUST redact
  sensitive fields (such as the authorization header and cookie) and MUST enable encryption at
  rest on the log destination (CloudWatch Logs, Amazon S3, or Amazon Data Firehose).
• Header-spoofing risk. Any x-amzn-waf-* signal forwarded to the origin can be forged inbound.
  You MUST add the inbound-header-stripping rule whenever a signal or client IP is forwarded (see
  stripping-inbound-waf-headers-before-trusting-them).

Additional Resources

• AWS WAF Developer Guide
• How AWS WAF works (AWS WAF Developer Guide)
• AWS WAF pricing