IAM Role Allows All Principals To Assume

• Query id: 12b7e704-37f0-4d1e-911a-44bf60c48c21
• Query name: IAM Role Allows All Principals To Assume
• Platform: Terraform
• Severity: Medium
• Category: Access Control
• URL: Github

Description

IAM role allows all services or principals to assume it
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - tf file

//  Create a role which OpenShift instances will assume.
//  This role has a policy saying it can be assumed by ec2
//  instances.
resource "aws_iam_role" "positive1" {
  name = "${var.name_tag_prefix}-openshift-instance-role"

  assume_role_policy = <<EOF
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": "sts:AssumeRole",
            "Principal": {
                "Service": "ec2.amazonaws.com"
            },
            "Effect": "Allow",
            "Sid": ""
        }
    ]
}
EOF
}

//  This policy allows an instance to forward logs to CloudWatch, and
//  create the Log Stream or Log Group if it doesn't exist.
resource "aws_iam_role" "positive2" {
  name        = "${var.name_tag_prefix}-openshift-instance-forward-logs"
  path        = "/"
  description = "Allows an instance to forward logs to CloudWatch"

  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Principal": {
        "AWS": "arn:aws:iam::root"
      },
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents",
        "logs:DescribeLogStreams"
    ],
      "Resource": [
        "arn:aws:iam::*:*:*"
    ]
  }
 ]
}
EOF
}


//  Attach the policies to the role.
resource "aws_iam_policy_attachment" "positive3" {
  name       = "${var.name_tag_prefix}-openshift-attachment-forward-logs"
  roles      = ["${aws_iam_role.openshift-instance-role.name}"]
  policy_arn = "${aws_iam_policy.openshift-policy-forward-logs.arn}"
}

//  Create a instance profile for the role.
resource "aws_iam_instance_profile" "positive4" {
  name  = "${var.name_tag_prefix}-openshift-instance-profile"
  role = "${aws_iam_role.openshift-instance-role.name}"
}

Code samples without security vulnerabilities

Negative test num. 1 - tf file

//  Create a role which OpenShift instances will assume.
//  This role has a policy saying it can be assumed by ec2
//  instances.
resource "aws_iam_role" "negative1" {
  name = "${var.name_tag_prefix}-openshift-instance-role"

  assume_role_policy = <<EOF
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": "sts:AssumeRole",
            "Principal": {
                "Service": "ec2.amazonaws.com"
            },
            "Effect": "Allow",
            "Sid": ""
        }
    ]
}
EOF
}

//  This policy allows an instance to forward logs to CloudWatch, and
//  create the Log Stream or Log Group if it doesn't exist.
resource "aws_iam_policy" "negative2" {
  name        = "${var.name_tag_prefix}-openshift-instance-forward-logs"
  path        = "/"
  description = "Allows an instance to forward logs to CloudWatch"

  policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Principal": {
        "AWS": "arn:aws:iam::some_role"
      },
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents",
        "logs:DescribeLogStreams"
    ],
      "Resource": [
        "arn:aws:iam::*:*:*"
    ]
  }
 ]
}
EOF
}


//  Attach the policies to the role.
resource "aws_iam_policy_attachment" "negative3" {
  name       = "${var.name_tag_prefix}-openshift-attachment-forward-logs"
  roles      = ["${aws_iam_role.openshift-instance-role.name}"]
  policy_arn = "${aws_iam_policy.openshift-policy-forward-logs.arn}"
}

//  Create a instance profile for the role.
resource "aws_iam_instance_profile" "negative4" {
  name  = "${var.name_tag_prefix}-openshift-instance-profile"
  role = "${aws_iam_role.openshift-instance-role.name}"
}