c1.15 Protect web applications
Shield your internet-facing applications from the most common web attacks with a web application firewall. The quickest path is AWS WAF with AWS-managed rule groups: protection in minutes, pay-per-use pricing, and low operational overhead.
Implementation guidance
Managed protection in minutes
AWS WAF attaches directly to Amazon CloudFront, Application Load Balancers, API Gateway, AppSync, and other front doors, so it is quick to deploy. Enable the AWS Managed Rules rule groups to get immediate coverage for the most common and critical attacks (aligned with the OWASP Top 10), plus reputation lists that block known-bad and botnet IPs. Optional managed groups add account-takeover prevention, bot control, and more.
Why it is a Quick Win
Most web apps must be exposed to serve users, which exposes any vulnerability in the app or its middleware. Secure coding is essential but takes time and expertise; a WAF is a fast, high-value layer that blocks exploitation while the deeper application-security work happens. It deploys in minutes, scales elastically, and its pay-per-use model keeps it low cost for most use cases.
Deploy consistently, then tune
Use AWS Firewall Manager to enforce a default WebACL across all CloudFront distributions, ALBs, and API Gateways in the organization, so no app is left unprotected. Start rules in count mode to observe, then switch to block once you have confirmed there are no false positives on legitimate traffic.
Beyond the Quick Win
For specialized needs you can layer partner WAF/security solutions from AWS Marketplace (F5, Fortinet, Imperva, and others), which keep WAF's easy deployment and elastic scaling. See WAF with custom rules for the later, deeper phase.
How it fits together
How to validate
- Is a WAF protecting all your internet-facing applications, and how is it deployed?
- Is AWS WAF deployed consistently across the organization (e.g. a default WebACL enforced via Firewall Manager for CloudFront, ALBs, and API Gateways)?
- Are the rules in block mode, or still only counting?
- Which AWS Managed Rules groups are active?
Threats addressed
- Internet-facing applications expose any vulnerability in the app or its middleware to adversaries. Managed WAF rules block the most common exploitation attempts before they reach the application.
- Development teams rarely have the time or specialization to harden against every web attack; a WAF provides an immediate protective layer while secure-coding practices mature.
AWS services
AWS WAF 
Amazon CloudFront 
AWS Firewall Manager Pricing
AWS WAF is pay-per-use: a monthly fee per web ACL and per rule, plus a charge per million requests inspected. AWS managed rule groups are included; AWS Marketplace rule groups add a subscription. See AWS WAF pricing.