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enable-waf

Default Severity: high

Explanation

You should configure a Web Application Firewall in front of your CloudFront distribution. This will mitigate many types of attacks on your web application.

Possible Impact

Complex web application attacks can more easily be performed without a WAF

Suggested Resolution

Enable WAF for the CloudFront distribution

Insecure Example

The following example will fail the aws-cloudfront-enable-waf check. 

 resource "aws_cloudfront_distribution" "bad_example" {
   origin_group {
     origin_id = "groupS3"

     failover_criteria {
       status_codes = [403, 404, 500, 502]
     }

     member {
       origin_id = "primaryS3"
     }
   }

   origin {
     domain_name = aws_s3_bucket.primary.bucket_regional_domain_name
     origin_id   = "primaryS3"

     s3_origin_config {
       origin_access_identity = aws_cloudfront_origin_access_identity.default.cloudfront_access_identity_path
     }
   }

   origin {
     domain_name = aws_s3_bucket.failover.bucket_regional_domain_name
     origin_id   = "failoverS3"

     s3_origin_config {
       origin_access_identity = aws_cloudfront_origin_access_identity.default.cloudfront_access_identity_path
     }
   }

   default_cache_behavior {
     target_origin_id = "groupS3"
   }
 }

Secure Example

The following example will pass the aws-cloudfront-enable-waf check. 

 resource "aws_cloudfront_distribution" "good_example" {

   origin {
     domain_name = aws_s3_bucket.primary.bucket_regional_domain_name
     origin_id   = "primaryS3"

     s3_origin_config {
       origin_access_identity = aws_cloudfront_origin_access_identity.default.cloudfront_access_identity_path
     }
   }

   origin {
     domain_name = aws_s3_bucket.failover.bucket_regional_domain_name
     origin_id   = "failoverS3"

     s3_origin_config {
       origin_access_identity = aws_cloudfront_origin_access_identity.default.cloudfront_access_identity_path
     }
   }

   default_cache_behavior {
     target_origin_id = "groupS3"
   }

   web_acl_id = "waf_id"
 }