IAM Policy Grants Full Permissions

• Query id: 575a2155-6af1-4026-b1af-d5bc8fe2a904
• Query name: IAM Policy Grants Full Permissions
• Platform: Terraform
• Severity: High
• Category: Access Control
• URL: Github

Description

IAM policy should not grant full permissions to resources from the get-go, instead of granting permissions gradually as necessary.
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

resource "aws_iam_user" "positive1" {
  name          = "${local.resource_prefix.value}-user"
  force_destroy = true

  tags = {
    Name        = "${local.resource_prefix.value}-user"
    Environment = local.resource_prefix.value
  }

}

resource "aws_iam_access_key" "positive2" {
  user = aws_iam_user.user.name
}

resource "aws_iam_user_policy" "positive3" {
  name = "excess_policy"
  user = aws_iam_user.user.name

  policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
      "*"
      ],
      "Effect": "Allow",
      "Resource": "*"
    }
  ]
}
EOF
}

output "username" {
  value = aws_iam_user.user.name
}

output "secret" {
  value = aws_iam_access_key.user.encrypted_secret
}

Positive test num. 2 - tf file

resource "aws_iam_policy" "s3-permission" {
  name   = "s3-permission"
  policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "*"
      ],
      "Effect": "Allow",
      "Resource": "*"
    }
  ]
}
EOF
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

resource "aws_iam_user" "negative1" {
  name          = "${local.resource_prefix.value}-user"
  force_destroy = true

  tags = {
    Name        = "${local.resource_prefix.value}-user"
    Environment = local.resource_prefix.value
  }

}

resource "aws_iam_access_key" "negative2" {
  user = aws_iam_user.user.name
}

resource "aws_iam_user_policy" "negative3" {
  name = "excess_policy"
  user = aws_iam_user.user.name

  policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "ec2:*",
        "s3:*",
        "lambda:*",
        "cloudwatch:*"
      ],
      "Effect": "Allow",
      "Resource": "SomeResource"
    }
  ]
}
EOF
}

output "username" {
  value = aws_iam_user.user.name
}

output "secret" {
  value = aws_iam_access_key.user.encrypted_secret
}

Negative test num. 2 - tf file

resource "aws_iam_policy" "s3-permission" {
  name   = "s3-permission"
  policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "ec2:*",
        "s3:*",
        "lambda:*",
        "cloudwatch:*"
      ],
      "Effect": "Allow",
      "Resource": "SomeResource"
    }
  ]
}
EOF
}

Negative test num. 3 - tf file

resource "aws_iam_policy" "s3-permission" {
  name   = "s3-permission"
  policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "*"
      ],
      "Effect": "Allow",
      "Resource": "arn:aws:iam::aws:policy/AdministratorAccess"
    }
  ]
}
EOF
}