User Data Contains Encoded Private Key

• Query id: 443488f5-c734-460b-a36d-5b3f330174dc
• Query name: User Data Contains Encoded Private Key
• Platform: Terraform
• Severity: High
• Category: Encryption
• URL: Github

Description

User Data should not contain a base64 encoded private key. If so, anyone can decode the private key easily
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

resource "aws_launch_configuration" "positive1" {
  image_id      = data.aws_ami.ubuntu.id
  instance_type = "m4.large"
  spot_price    = "0.001"
  user_data_base64 = "LS0tLS1CRUdJTiBSU0EgUFJJVkFURSBLRVktLS0tLQpzb21lS2V5" # someKey

  lifecycle {
    create_before_destroy = true
  }
}

Positive test num. 2 - tf file

module "positive2" {
  source = "terraform-aws-modules/autoscaling/aws"
  version = "1.0.4"

  # Launch configuration
  lc_name = "example-lc"

  image_id        = "ami-ebd02392"
  instance_type   = "t2.micro"
  security_groups = ["sg-12345678"]
  user_data_base64 = "LS0tLS1CRUdJTiBSU0EgUFJJVkFURSBLRVktLS0tLQpzb21lS2V5"

  ebs_block_device = [
    {
      device_name           = "/dev/xvdz"
      volume_type           = "gp2"
      volume_size           = "50"
      delete_on_termination = true
    },
  ]

  root_block_device = [
    {
      volume_size = "50"
      volume_type = "gp2"
    },
  ]

  # Auto scaling group
  asg_name                  = "example-asg"
  vpc_zone_identifier       = ["subnet-1235678", "subnet-87654321"]
  health_check_type         = "EC2"
  min_size                  = 0
  max_size                  = 1
  desired_capacity          = 1
  wait_for_capacity_timeout = 0

  tags = [
    {
      key                 = "Environment"
      value               = "dev"
      propagate_at_launch = true
    },
    {
      key                 = "Project"
      value               = "megasecret"
      propagate_at_launch = true
    },
  ]
}

Positive test num. 3 - tf file

module "positive3" {
  source = "terraform-aws-modules/autoscaling/aws"
  version = "1.0.4"

  # Launch configuration
  lc_name = "example-lc"

  image_id        = "ami-ebd02392"
  instance_type   = "t2.micro"
  security_groups = ["sg-12345678"]
  user_data_base64 = "LS0tLS1CRUdJTiBPUEVOU1NIIFBSSVZBVEUgS0VZIEJMT0NLLS0tLS0="

  ebs_block_device = [
    {
      device_name           = "/dev/xvdz"
      volume_type           = "gp2"
      volume_size           = "50"
      delete_on_termination = true
    },
  ]

  root_block_device = [
    {
      volume_size = "50"
      volume_type = "gp2"
    },
  ]

  # Auto scaling group
  asg_name                  = "example-asg"
  vpc_zone_identifier       = ["subnet-1235678", "subnet-87654321"]
  health_check_type         = "EC2"
  min_size                  = 0
  max_size                  = 1
  desired_capacity          = 1
  wait_for_capacity_timeout = 0

  tags = [
    {
      key                 = "Environment"
      value               = "dev"
      propagate_at_launch = true
    },
    {
      key                 = "Project"
      value               = "megasecret"
      propagate_at_launch = true
    },
  ]
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

resource "aws_launch_configuration" "negative1" {
  image_id      = data.aws_ami.ubuntu.id
  instance_type = "m4.large"
  spot_price    = "0.001"

  lifecycle {
    create_before_destroy = true
  }
}

resource "aws_launch_configuration" "negative2" {
  image_id      = data.aws_ami.ubuntu.id
  instance_type = "m4.large"
  spot_price    = "0.001"
  user_data_base64 = ""

  lifecycle {
    create_before_destroy = true
  }
}

resource "aws_launch_configuration" "negative3" {
  image_id      = data.aws_ami.ubuntu.id
  instance_type = "m4.large"
  spot_price    = "0.001"
  user_data_base64 = "dGVzdA=="

  lifecycle {
    create_before_destroy = true
  }
}

resource "aws_launch_configuration" "negative4" {
  image_id      = data.aws_ami.ubuntu.id
  instance_type = "m4.large"
  spot_price    = "0.001"
  user_data_base64 = null

  lifecycle {
    create_before_destroy = true
  }
}