securing-api-gateway-with-aws-waf

What this skill does

# Securing API Gateway with AWS WAF

## When to Use

- When deploying API Gateway endpoints that require protection against common web attacks
- When implementing rate limiting and throttling to prevent API abuse and DDoS attacks
- When building bot detection and mitigation for API endpoints exposed to the internet
- When compliance requires WAF protection for all public-facing API endpoints
- When customizing access controls based on IP reputation, geolocation, or request patterns

**Do not use** for network-level DDoS protection (use AWS Shield), for application logic vulnerabilities (use SAST/DAST tools), or for internal API security between microservices (use service mesh authentication and authorization).

## Prerequisites

- AWS API Gateway (REST or HTTP API) deployed with public endpoints
- IAM permissions for `wafv2:*` and `apigateway:*` operations
- CloudWatch and S3 or Kinesis Firehose configured for WAF logging
- Understanding of the API's expected traffic patterns for rate limiting configuration
- IP reputation lists or threat intelligence feeds for custom IP blocking

## Workflow

### Step 1: Create a WAF Web ACL with Managed Rule Groups

Create a Web ACL with AWS Managed Rules for baseline protection against OWASP Top 10 attacks.

```bash
# Create a WAF Web ACL with managed rule groups
aws wafv2 create-web-acl \
  --name api-gateway-waf \
  --scope REGIONAL \
  --default-action '{"Allow":{}}' \
  --visibility-config '{
    "SampledRequestsEnabled": true,
    "CloudWatchMetricsEnabled": true,
    "MetricName": "api-gateway-waf"
  }' \
  --rules '[
    {
      "Name": "AWSManagedRulesCommonRuleSet",
      "Priority": 1,
      "Statement": {
        "ManagedRuleGroupStatement": {
          "VendorName": "AWS",
          "Name": "AWSManagedRulesCommonRuleSet"
        }
      },
      "OverrideAction": {"None": {}},
      "VisibilityConfig": {
        "SampledRequestsEnabled": true,
        "CloudWatchMetricsEnabled": true,
        "MetricName": "CommonRuleSet"
      }
    },
    {
      "Name": "AWSManagedRulesKnownBadInputsRuleSet",
      "Priority": 2,
      "Statement": {
        "ManagedRuleGroupStatement": {
          "VendorName": "AWS",
          "Name": "AWSManagedRulesKnownBadInputsRuleSet"
        }
      },
      "OverrideAction": {"None": {}},
      "VisibilityConfig": {
        "SampledRequestsEnabled": true,
        "CloudWatchMetricsEnabled": true,
        "MetricName": "KnownBadInputs"
      }
    },
    {
      "Name": "AWSManagedRulesSQLiRuleSet",
      "Priority": 3,
      "Statement": {
        "ManagedRuleGroupStatement": {
          "VendorName": "AWS",
          "Name": "AWSManagedRulesSQLiRuleSet"
        }
      },
      "OverrideAction": {"None": {}},
      "VisibilityConfig": {
        "SampledRequestsEnabled": true,
        "CloudWatchMetricsEnabled": true,
        "MetricName": "SQLiRuleSet"
      }
    },
    {
      "Name": "AWSManagedRulesAmazonIpReputationList",
      "Priority": 4,
      "Statement": {
        "ManagedRuleGroupStatement": {
          "VendorName": "AWS",
          "Name": "AWSManagedRulesAmazonIpReputationList"
        }
      },
      "OverrideAction": {"None": {}},
      "VisibilityConfig": {
        "SampledRequestsEnabled": true,
        "CloudWatchMetricsEnabled": true,
        "MetricName": "IPReputationList"
      }
    }
  ]'
```

### Step 2: Add Rate Limiting Rules

Configure rate-based rules to throttle excessive API requests per IP address.

```bash
# Get the Web ACL ARN and lock token
WEB_ACL_ARN=$(aws wafv2 list-web-acls --scope REGIONAL \
  --query "WebACLs[?Name=='api-gateway-waf'].ARN" --output text)

# Update Web ACL to add rate limiting rule
aws wafv2 update-web-acl \
  --name api-gateway-waf \
  --scope REGIONAL \
  --id $(aws wafv2 list-web-acls --scope REGIONAL --query "WebACLs[?Name=='api-gateway-waf'].Id" --output text) \
  --lock-token $(aws wafv2 get-web-acl --name api-gateway-waf --scope REGIONAL --id WEB_ACL_ID --query 'LockToken' --output text) \
  --default-action '{"Allow":{}}' \
  --visibility-config '{
    "SampledRequestsEnabled": true,
    "CloudWatchMetricsEnabled": true,
    "MetricName": "api-gateway-waf"
  }' \
  --rules '[
    {
      "Name": "RateLimitPerIP",
      "Priority": 0,
      "Statement": {
        "RateBasedStatement": {
          "Limit": 2000,
          "AggregateKeyType": "IP"
        }
      },
      "Action": {"Block": {}},
      "VisibilityConfig": {
        "SampledRequestsEnabled": true,
        "CloudWatchMetricsEnabled": true,
        "MetricName": "RateLimitPerIP"
      }
    },
    {
      "Name": "RateLimitLoginEndpoint",
      "Priority": 5,
      "Statement": {
        "RateBasedStatement": {
          "Limit": 100,
          "AggregateKeyType": "IP",
          "ScopeDownStatement": {
            "ByteMatchStatement": {
              "FieldToMatch": {"UriPath": {}},
              "PositionalConstraint": "STARTS_WITH",
              "SearchString": "/api/auth/login",
              "TextTransformations": [{"Priority": 0, "Type": "LOWERCASE"}]
            }
          }
        }
      },
      "Action": {"Block": {}},
      "VisibilityConfig": {
        "SampledRequestsEnabled": true,
        "CloudWatchMetricsEnabled": true,
        "MetricName": "RateLimitLogin"
      }
    }
  ]'
```

### Step 3: Implement Bot Control

Add AWS WAF Bot Control to detect and manage automated traffic.

```bash
# Add Bot Control managed rule group
# (Add to the rules array when updating the Web ACL)
{
  "Name": "AWSManagedRulesBotControlRuleSet",
  "Priority": 6,
  "Statement": {
    "ManagedRuleGroupStatement": {
      "VendorName": "AWS",
      "Name": "AWSManagedRulesBotControlRuleSet",
      "ManagedRuleGroupConfigs": [{
        "AWSManagedRulesBotControlRuleSet": {
          "InspectionLevel": "COMMON"
        }
      }],
      "ExcludedRules": [
        {"Name": "CategoryHttpLibrary"},
        {"Name": "SignalNonBrowserUserAgent"}
      ]
    }
  },
  "OverrideAction": {"None": {}},
  "VisibilityConfig": {
    "SampledRequestsEnabled": true,
    "CloudWatchMetricsEnabled": true,
    "MetricName": "BotControl"
  }
}
```

### Step 4: Create Custom Rules for API-Specific Protection

Build custom WAF rules for API-specific security requirements.

```bash
# Block requests without required API key header
{
  "Name": "RequireAPIKey",
  "Priority": 7,
  "Statement": {
    "NotStatement": {
      "Statement": {
        "ByteMatchStatement": {
          "FieldToMatch": {
            "SingleHeader": {"Name": "x-api-key"}
          },
          "PositionalConstraint": "EXACTLY",
          "SearchString": "",
          "TextTransformations": [{"Priority": 0, "Type": "NONE"}]
        }
      }
    }
  },
  "Action": {"Block": {"CustomResponse": {"ResponseCode": 403}}},
  "VisibilityConfig": {
    "SampledRequestsEnabled": true,
    "CloudWatchMetricsEnabled": true,
    "MetricName": "RequireAPIKey"
  }
}

# Geo-restrict to allowed countries
{
  "Name": "GeoRestriction",
  "Priority": 8,
  "Statement": {
    "NotStatement": {
      "Statement": {
        "GeoMatchStatement": {
          "CountryCodes": ["US", "CA", "GB", "DE", "FR", "AU"]
        }
      }
    }
  },
  "Action": {"Block": {}},
  "VisibilityConfig": {
    "SampledRequestsEnabled": true,
    "CloudWatchMetricsEnabled": true,
    "MetricName": "GeoRestriction"
  }
}

# Block oversized request bodies (prevent payload attacks)
{
  "Name": "MaxBodySize",
  "Priority": 9,
  "Statement": {
    "SizeConstraintStatement": {
      "FieldToMatch": {"Body": {"OversizeHandling": "MATCH"}},
      "ComparisonOperator": "GT",
      "Size": 10240,
      "TextTransformations": [{"Priority": 0, "Type": "NONE"}]
    }
  },
  "Action": {"Block": {}},
  "VisibilityConfig": {
    "SampledRequestsEnabled": true,
    "CloudWatchMetricsEnabled": true,
    "MetricName": "MaxBodySize"
  }
}
```

### Step 5: Associate WAF with API Gateway and Enable Logging

Attach the Web ACL to the API Gateway stage and configure