Service Account Roles at Project Level

ID: gcloud-iam-service-roles-project-level

Severity: medium

Author: princechaddha

Tags: cloud,devops,gcp,gcloud,google-cloud-iam,gcp-cloud-config

Description

Ensure that the Service Account User and Service Account Token Creator roles are assigned to a user for a specific GCP service account rather than to a user at the GCP project level, in order to implement the principle of least privilege (POLP). The principle of least privilege (also known as the principle of minimal privilege) is the practice of providing every user the minimal amount of access required to perform its tasks. The Service Account User (iam.serviceAccountUser) role allows an IAM user to attach a service account to a long-running job service such as an App Engine App or Dataflow Job, whereas the Service Account Token Creator (iam.serviceAccountTokenCreator) role allows a user to directly impersonate the identity of a service account.

YAML Source

id: gcloud-iam-service-roles-project-level

info:
  name: Service Account Roles at Project Level
  author: princechaddha
  severity: medium
  description: |
    Ensure that the Service Account User and Service Account Token Creator roles are assigned to a user for a specific GCP service account rather than to a user at the GCP project level, in order to implement the principle of least privilege (POLP). The principle of least privilege (also known as the principle of minimal privilege) is the practice of providing every user the minimal amount of access required to perform its tasks. The Service Account User (iam.serviceAccountUser) role allows an IAM user to attach a service account to a long-running job service such as an App Engine App or Dataflow Job, whereas the Service Account Token Creator (iam.serviceAccountTokenCreator) role allows a user to directly impersonate the identity of a service account.
  impact: |
    Assigning critical roles such as Service Account User and Token Creator at the project level can lead to excessive permissions that can be exploited.
  remediation: |
    Ensure these roles are assigned directly to service accounts and not at the project level to enforce the principle of least privilege.
  reference:
    - https://cloud.google.com/iam/docs/understanding-roles
  tags: cloud,devops,gcp,gcloud,google-cloud-iam,gcp-cloud-config

flow: |
  code(1)
  for(let projectId of iterate(template.projectIds)){
    set("projectId", projectId)
    code(2)
    for(let binding of iterate(template.bindings)){
        set("binding", binding)
        javascript(1);
    }
  }

self-contained: true

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

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

  - engine:
      - sh
      - bash
    source: |
      gcloud projects get-iam-policy $projectId --format=json

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

javascript:
  - code: |
        let binding = JSON.parse(template.binding);
        let projectId = template.projectId;
        if (binding.role == "roles/iam.serviceAccountUser" && binding.role == "roles/iam.serviceAccountTokenCreator"){
          Export("Service Role Misconfiguration for role " + binding.role + " for member " + binding.members + " in Project " + projectId);
        }

    extractors:
      - type: dsl
        dsl:
          - response
# digest: 4b0a00483046022100caa8c57237fa231d6653f2d83fa719f24133549a2df932fde71ec14dfa003c2b022100944cbd22c9b1be4e04f3605258b3cd1646fec559d5900fe12fc2f4ee24c2f3e0:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

This template is used to detect vulnerabilities in web applications. It can be used with the Nuclei tool to scan for specific patterns or behaviors.

$ nuclei -u "URL" -t "cloud/gcp/iam/gcloud-iam-service-roles-project-level.yaml"

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