Group with privilege escalation by actions 'iam:PutGroupPolicy'

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Metadata

Id: e77c89f6-9c85-49ea-b95b-5f960fe5be92

Cloud Provider: AWS

Platform: Terraform

Severity: Medium

Category: Access Control

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Description

This check identifies IAM group policies that grant the action iam:PutGroupPolicy with a resource set to "*", allowing anyone in the group to attach arbitrary inline policies to any IAM group. This presents a privilege escalation risk, as users with this permission could assign themselves broader or unauthorized permissions by updating policies on other groups. To mitigate this, restrict the Action and Resource fields in policies and avoid assigning sensitive permissions to groups broadly.

A secure Terraform configuration should limit permissions to only what is necessary. For example:

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 = "*"
      },
    ]
  })
}

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:PutGroupPolicy",
        ]
        Effect   = "Allow"
        Resource = "*"
      },
    ]
  })
}