Aligent AWS WAF

Overview

This repository defines a CDK construct for provisioning an AWS Web Application Firewall (WAF) stack. It can be imported and used within CDK application. ##Example The following CDK snippet can be used to provision the an AWS WAF stack.

import 'source-map-support/register';
const cdk = require('@aws-cdk/core');
import { WebApplicationFirewall } from '@aligent/cdk-waf';
import { Stack } from '@aws-cdk/core';


import { Environment } from '@aws-cdk/core'
import { env } from 'node:process';

const preprodEnv: Environment = {account: '<TargetAccountId-Preprod>', region: '<TargetAccountRegion-Preprod>'};

const target = '<TargetAccountIdentifier>';
const appName = 'WAF';

const defaultAllowedIPv4s = [
     'a.a.a.a/32', 'b.b.b.b/32',     // Offices
     'c.c.c.c/32', 'd.d.d.d/32',     // Payment Gateways
]

const defaultAllowedIPv6s = [
     '1234:abcd:5678:ef01::/56',     // Offices
     '1234:ef01:5678:abcd::/56',     // Security Scanner
]

export const preProductionWafStackProps = {
env: preprodEnv,
     activate: true,  // Update this line with either true or false, defining Block mode or Count-only mode, respectively.  
     allowedIPs: defaultAllowedIPs.concat([
               'y.y.y.y/32' // AWS NAT GW of preprod vpc
               // environment-specific comma-separated allow-list comes here
     ]),
     allowedUserAgents: [],  // Allowed User-Agent list that would have been blocked by AWS BadBot rule. Case-sensitive. Optional.
     excludedAwsRules: [],   // The rule to exclude (override) from AWS-managed RuleSet. Optional.
     associatedLoadBalancerArn: '<ArnOfPreproductionFrontendALB>',
     wafName: <NAME>
}

class WAFStack extends Stack {
  constructor(scope: Construct, id: string, props: preprodEnv) {
    super(scope, id, props);

    new WebApplicationFirewall(scope, 'waf-stack', prod);
  }
}

new WAFStack(scope, envName, preProductionWafStackProps);

Monitor and activate

By default, WebACL this stack creates will work in COUNT mode to begin with.After a certain period of monitoring under real traffic and load, apply necessary changes, e.g. IP allow_list or rate limit, to avoid service interruptions before switching to BLOCK mode.

Local development

NPM link can be used to develop the module locally.

1. Pull this repository locally
2. cd into this repository
3. run npm link
4. cd into the downstream repo (target project, etc) and run npm link '@aligent/cdk-waf' The downstream repository should now include a symlink to this module. Allowing local changes to be tested before pushing. You may want to update the version notation of the package in the downstream repository's package.json.