S3 Bucket ACL Allows Read to Any Authenticated User

• Query id: 57b9893d-33b1-4419-bcea-a717ea87e139
• Query name: S3 Bucket ACL Allows Read to Any Authenticated User
• Platform: Terraform
• Severity: High
• Category: Access Control
• URL: Github

Description

S3 Buckets should not be readable to any authenticated user
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

provider "aws" {
  region = "us-east-1"
}

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.0"
    }
  }
}

resource "aws_s3_bucket" "positive1" {
  bucket = "my-tf-test-bucket"
  acl    = "authenticated-read"

  tags = {
    Name        = "My bucket"
    Environment = "Dev"
  }
}

Positive test num. 2 - tf file

module "s3_bucket" {
  source = "terraform-aws-modules/s3-bucket/aws"
  version = "3.7.0"

  bucket = "my-s3-bucket"
  acl    = "authenticated-read"

  versioning = {
    enabled = true
  }
}

Positive test num. 3 - tf file

provider "aws" {
  region = "us-east-1"
}

terraform {
  required_providers {
    aws = {
      source = "hashicorp/aws"
      version = "4.2.0"
    }
  }
}

resource "aws_s3_bucket" "example1" {
  bucket = "my-tf-example-bucket"
}

resource "aws_s3_bucket_acl" "example_bucket_acl" {
  bucket = aws_s3_bucket.example1.id
  acl    = "authenticated-read"
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

provider "aws" {
  region = "us-east-1"
}

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 3.0"
    }
  }
}

resource "aws_s3_bucket" "negative1" {
  bucket = "my-tf-test-bucket"
  acl    = "private"

  tags = {
    Name        = "My bucket"
    Environment = "Dev"
  }
}

Negative test num. 2 - tf file

module "s3_bucket" {
  source = "terraform-aws-modules/s3-bucket/aws"
  version = "3.7.0"

  bucket = "my-s3-bucket"
  acl    = "private"

  versioning = {
    enabled = true
  }
}

Negative test num. 3 - tf file

provider "aws" {
  region = "us-east-1"
}

terraform {
  required_providers {
    aws = {
      source = "hashicorp/aws"
      version = "4.2.0"
    }
  }
}

resource "aws_s3_bucket" "example0" {
  bucket = "my-tf-example-bucket"
}

resource "aws_s3_bucket_acl" "example_bucket_acl" {
  bucket = aws_s3_bucket.example0.id
  acl    = "private"
}