Group with privilege escalation by actions 'iam:AttachUserPolicy'

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Metadata

Id: db78d14b-10e5-4e6e-84b1-dace6327b1ec

Cloud Provider: AWS

Platform: Terraform

Severity: Medium

Category: Access Control

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Description

Granting a group the iam:AttachUserPolicy action with "Resource": "*" in Terraform, as shown by the attribute and policy below, allows any group member to attach arbitrary IAM policies to any user in the AWS account. This creates a serious privilege escalation vulnerability, as users with this permission can grant themselves or others higher privileges, including administrative access, bypassing intended security controls. If left unaddressed, attackers could exploit this misconfiguration to gain unrestricted access or take over AWS resources.

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

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_group" "cosmic" {
  name = "cosmic"
}

resource "aws_iam_group_policy" "test_inline_policy" {
  name = "test_inline_policy"
  group = aws_iam_group.cosmic.name

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