User with privilege escalation by actions 'iam:CreatePolicyVersion'

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Metadata

Id: 1743f5f1-0bb0-4934-acef-c80baa5dadfa

Cloud Provider: AWS

Platform: Terraform

Severity: Medium

Category: Access Control

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Description

Allowing a user the iam:CreatePolicyVersion action with the resource set to "*" in Terraform, as shown in the policy statement below, enables them to update any IAM policy in the AWS account. This privilege can be exploited for privilege escalation, as the user could create a new policy version attaching elevated permissions to themselves or others.

policy = jsonencode({
  Version = "2012-10-17"
  Statement = [
    {
      Action = [
        "iam:CreatePolicyVersion",
      ]
      Effect   = "Allow"
      Resource = "*"
    },
  ]
})

If left unaddressed, this misconfiguration could allow an attacker to gain unauthorized administrative access or perform malicious actions across your AWS environment by changing permissions on any IAM policy.

Compliant Code Examples

resource "aws_iam_user" "cosmic2" {
  name = "cosmic2"
}

resource "aws_iam_user_policy" "inline_policy_run_instances2" {
  name = "inline_policy_run_instances"
  user = aws_iam_user.cosmic2.name

  policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = [
          "ec2:Describe*",
        ]
        Effect   = "Allow"
        Resource = "*"
      },
    ]
  })
}

Non-Compliant Code Examples

resource "aws_iam_user" "cosmic" {
  name = "cosmic"
}

resource "aws_iam_user_policy" "test_inline_policy" {
  name = "test_inline_policy"
  user = aws_iam_user.cosmic.name

  policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = [
          "iam:CreatePolicyVersion",
        ]
        Effect   = "Allow"
        Resource = "*"
      },
    ]
  })
}


resource "aws_iam_policy_attachment" "test-attach" {
  name       = "test-attachment"
  users      = [aws_iam_user.cosmic.name]
  roles      = [aws_iam_role.role.name]
  groups     = [aws_iam_group.group.name]
}