id: gcloud-org-vpn-peer-ips

info:
  name: VPN Peer IP Addresses Not Restricted
  author: princechaddha
  severity: medium
  description: |
    Ensure that only trusted IPv4 addresses can be configured as VPN peer IPs within your Google Cloud organization. By enforcing the "Restrict VPN Peer IPs" constraint policy, you can control the IP addresses that can be configured as VPN peer IPs within your Google Cloud organization in order to meet security and compliance requirements.
  impact: |
    By default, any IP address can be a VPN peer IP for a Virtual Private Cloud (VPC) network. Without restrictions, this could allow unauthorized or malicious networks to establish VPN connections with your VPC.
  remediation: |
    Configure the "Restrict VPN Peer IPs" policy at the organization level to explicitly specify which IPv4 addresses can be configured as VPN peer IPs. Use space-separated IP addresses in the policy configuration.
  reference:
    - https://www.trendmicro.com/cloudoneconformity/knowledge-base/gcp/ResourceManager/restrict-vpn-peer-ips.html
    - https://cloud.google.com/vpc/docs/using-vpn
  tags: cloud,devops,gcp,gcloud,resourcemanager,security,networking,vpn,gcp-cloud-config

flow: |
  code(1)
  for(let orgId of iterate(template.orgIds)){
    set("orgId", orgId)
    code(2)
  }

self-contained: true

code:
  - engine:
      - sh
      - bash
    source: |
      gcloud organizations list --format="json(name)"

    extractors:
      - type: json
        name: orgIds
        internal: true
        json:
          - '.[].name'

  - engine:
      - sh
      - bash
    source: |
      gcloud alpha resource-manager org-policies describe compute.restrictVpnPeerIPs --organization=$orgId --effective --format="json(listPolicy.allValues)"

    matchers:
      - type: word
        words:
          - "ALLOW"

    extractors:
      - type: dsl
        dsl:
          - '"Organization " + orgId + " has not restricted VPN peer IP addresses, allowing any IP to be configured as a VPN peer"'
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