performing-gcp-penetration-testing-with-gcpbucketbrute

name	performing-gcp-penetration-testing-with-gcpbucketbrute
description	Perform GCP security testing using GCPBucketBrute for storage bucket enumeration, gcloud IAM privilege escalation path analysis, and service account permission auditing
domain	cybersecurity
subdomain	cloud-security
tags	["gcp","cloud-pentesting","bucket-enumeration","iam-audit","privilege-escalation","gcpbucketbrute"]
version	1.0
author	mahipal
license	Apache-2.0
nist_ai_rmf	["MEASURE-2.7","MAP-5.1","MANAGE-2.4"]
atlas_techniques	["AML.T0070","AML.T0066","AML.T0082"]
nist_csf	["PR.IR-01","ID.AM-08","GV.SC-06","DE.CM-01"]

Performing GCP Penetration Testing with GCPBucketBrute

Overview

This skill covers Google Cloud Platform security testing using GCPBucketBrute for storage bucket enumeration and access permission testing, combined with gcloud CLI IAM enumeration to identify privilege escalation paths. The approach tests for publicly accessible buckets, overly permissive IAM bindings, and service account key exposure.

When to Use

• When conducting security assessments that involve performing gcp penetration testing with gcpbucketbrute
• When following incident response procedures for related security events
• When performing scheduled security testing or auditing activities
• When validating security controls through hands-on testing

Most Often Missed & How to Confirm

• Run both unauthenticated AND authenticated: GCPBucketBrute tests anonymous access by default, but a bucket that 403s anonymously may grant storage.objects.list to allAuthenticatedUsers (any Google account). Run it again with a logged-in account (omit -u) or you'll miss this entire class.
• Custom keywords matter: the default permutation set misses real buckets that use project/app prefixes. Feed company-specific terms via -k/--keyword plus a custom wordlist.
• Check write, not just read: TestIamPermissions reports the caller's perms - look for storage.buckets.setIamPolicy and storage.objects.create, not only storage.objects.get. Write/ACL access is the higher-impact, commonly-skipped finding.
• IAM privesc beyond project roles: check iam.serviceAccounts.actAs, iam.serviceAccounts.getAccessToken, iam.serviceAccountKeys.create, and setIamPolicy at project/folder/org level via gcloud projects get-iam-policy and gcloud iam service-accounts get-iam-policy. roles/iam.serviceAccountTokenCreator over a higher-priv SA = full impersonation.
• Default Compute/AppEngine SAs frequently retain roles/editor - check them explicitly.

How to confirm a hit (avoid false negatives): a permission returned by TestIamPermissions is a claim - prove it. Actually gsutil ls gs://bucket and gsutil cp a test object for read/write; for impersonation run and use the token. you tested both unauth and authenticated, enumerated with custom keywords, walked /token-creator chains, and inspected the default service accounts.