S3 Bucket ACL Grants WRITE_ACP Permission

Query id: 64a222aa-7793-4e40-915f-4b302c76e4d4
Query name: S3 Bucket ACL Grants WRITE_ACP Permission
Platform: Terraform
Severity: Critical
Category: Access Control
CWE: 732
URL: Github

Description¶

S3 Buckets should not allow WRITE_ACP permission to the S3 Bucket Access Control List in order to prevent AWS accounts or IAM users to modify access control permissions to the bucket.
Documentation

Code samples¶

Code samples with security vulnerabilities¶

Positive test num. 1 - tf file

data "aws_canonical_user_id" "current" {}

resource "aws_s3_bucket" "example" {
  bucket = "my-tf-example-bucket"
}

resource "aws_s3_bucket_acl" "example" {
  bucket = aws_s3_bucket.example.id
  access_control_policy {

    grant {
      grantee {
        type = "Group"
        uri  = "http://acs.amazonaws.com/groups/s3/LogDelivery"
      }
      permission = "WRITE_ACP"
    }

    owner {
      id = data.aws_canonical_user_id.current.id
    }
  }
}

Positive test num. 2 - tf file

data "aws_canonical_user_id" "current" {}

resource "aws_s3_bucket" "example" {
  bucket = "my-tf-example-bucket"
}

resource "aws_s3_bucket_acl" "example" {
  bucket = aws_s3_bucket.example.id
  access_control_policy {
    grant {
      grantee {
        id   = data.aws_canonical_user_id.current.id
        type = "CanonicalUser"
      }
      permission = "READ"
    }

    grant {
      grantee {
        type = "Group"
        uri  = "http://acs.amazonaws.com/groups/s3/LogDelivery"
      }
      permission = "WRITE_ACP"
    }

    owner {
      id = data.aws_canonical_user_id.current.id
    }
  }
}

Code samples without security vulnerabilities¶

Negative test num. 1 - tf file

data "aws_canonical_user_id" "current" {}

resource "aws_s3_bucket" "example" {
  bucket = "my-tf-example-bucket"
}

resource "aws_s3_bucket_acl" "example" {
  bucket = aws_s3_bucket.example.id
  access_control_policy {
    grant {
      grantee {
        id   = data.aws_canonical_user_id.current.id
        type = "CanonicalUser"
      }
      permission = "READ"
    }

    grant {
      grantee {
        type = "Group"
        uri  = "http://acs.amazonaws.com/groups/s3/LogDelivery"
      }
      permission = "READ_ACP"
    }

    owner {
      id = data.aws_canonical_user_id.current.id
    }
  }
}