Google Cloud keeps its data centers, hardware, and core services secure. Everything your team builds on top of them is yours to secure: who gets access to which project, what each service account can touch, which storage buckets are public, and how your Kubernetes clusters are set up. That split is called the shared responsibility model, and it’s why a clean bill of health from Google says nothing about your own setup.
A GCP penetration test checks your half. Testers start with a level of access an attacker could realistically get, such as a leaked key or a low-level account, and see how far it takes them. CYBRI’s GCP penetration testing guide explains the scope in more detail.
This list compares five US-based firms that test Google Cloud environments, and the kind of company each one fits best.
The five companies on this list:
- CYBRI: best for SaaS companies on Google Cloud that want manual-first testing of the cloud and the app in one engagement
- Rhino Security Labs: best for teams that want a cloud-focused firm to dig deep into GCP permissions and GKE
- Bishop Fox: best for large companies running GCP alongside AWS or Azure
- Mandiant (Google Cloud): best for enterprises that want testing shaped by Google’s own incident response work
- GuidePoint Security: best for mid-size and large companies that want cloud testing from the same partner that handles their wider security program
Why Google Cloud Needs Its Own Pentest
A standard network or web app test doesn’t cover the cloud control layer: the permissions, keys, and settings that decide who can do what inside your Google Cloud organization. That layer is where most cloud incidents start, and two things make GCP worth testing on its own terms.
Service Accounts Hold the Keys
Google Cloud gives each app, script, and virtual machine its own identity, called a service account. Those accounts often carry far more permission than the job needs, because broad roles are faster to set up than narrow ones. If an attacker gets hold of one service account key, through a public code repository, a misconfigured server, or a compromised developer laptop, the question becomes how far that single key reaches.
A cloud pentester answers that by hand. They map which roles each identity holds, look for chains where one permission lets an attacker grant themselves another, and check whether access in one project leads into others. Automated posture tools can flag a risky setting. They rarely show the path an attacker would walk from that setting to your customer data.
Google Doesn’t Need to Approve the Test
You don’t need Google’s permission to test your own GCP resources. Testers follow Google Cloud’s Acceptable Use Policy and Terms of Service, which rule out activity such as attacking other customers or flooding shared infrastructure. That makes a GCP test easier to schedule than many buyers expect.
Auditors look at results the same way on any platform. SOC 2, ISO 27001, PCI DSS, and HIPAA reviews all look for evidence that the systems holding customer data were tested and that findings were fixed. If your product runs on Google Cloud, that evidence should include the cloud setup itself. CYBRI’s GCP best practices guide covers the settings worth fixing before testers arrive.
How These Companies Were Chosen
Each firm had to clear the same bar before its “best for” line was written:
- Based in the United States. All five companies are US-based.
- Google Cloud named in writing. The firm’s own pages list GCP or Google Cloud as a platform it tests, not only “cloud” in general.
- People lead the testing. Tools help map the environment. A person decides how to chain permissions and what each finding means.
- Experienced testers. Hands-on certifications such as OSCP, or a long public record of cloud security work.
- A clear fit. Each firm does something specific well, which is what its “best for” line describes.
Crowdsourced platforms and AI-first products were left out. Cloud permission testing depends on a known team learning how your projects, roles, and services connect.
The 5 Best GCP Penetration Testing Companies in 2026
1. CYBRI
Best for: SaaS companies on Google Cloud that want manual-first testing of the cloud and the app in one engagement
CYBRI is a New York penetration testing company founded in 2017, and its testing is manual-first by design. Automated tools help map what’s there. OSCP-certified testers (OSCP is a hands-on certification earned by breaking into live systems) then do the actual attacking by hand. On a GCP penetration test, scope covers IAM roles and policies, service accounts, Compute Engine virtual machines, Cloud Storage, Cloud SQL and other managed databases, GKE clusters, Cloud Functions, and the firewall rules and load balancers in front of them.
What makes CYBRI a natural fit for SaaS teams is that the cloud rarely gets tested alone. The same testers can sign in to your app as each user role and follow a finding from the web front end down into the Google Cloud project behind it. A report that shows that full path is what an engineering lead needs to prioritize, and what an enterprise customer’s security team wants to see.
Critical findings are flagged the same day they’re confirmed. Reports pair an executive summary for leadership and auditors with technical findings scored on CVSS 4.0, plus GCP-specific fixes, mapped to SOC 2, ISO 27001, PCI DSS, and HIPAA. The testers work with your engineers while they patch, and a retest within the 90-day remediation window confirms each fix and produces an updated report.
2. Rhino Security Labs
Best for: teams that want a cloud-focused firm to dig deep into GCP permissions and GKE
Benjamin Caudill founded Rhino Security Labs in Seattle in 2013, and cloud testing across AWS, Azure, and GCP is one of its main lines of work. Its GCP assessment is an authenticated look at the environment: testers get the same level of access an attacker would have after a foothold, then check privilege escalation paths for every user and service account, including escalation across projects and organizations.
The scope goes well past IAM. Testers analyze and try to exploit Kubernetes Engine configuration, review Cloud Functions code, test pivots through shared VPCs and VPC peering, and check whether your controls would notice data being pulled out of VMs, storage, and databases. Logging, monitoring, and encryption settings are part of the review too. Each report lists every finding with a risk rating and fix guidance, plus a written attack narrative for any complex path the testers took. Urgent issues are reported as soon as they’re found.
3. Bishop Fox
Best for: large companies running GCP alongside AWS or Azure
Bishop Fox is based in Tempe, Arizona, and has worked in offensive security for more than 20 years. Its cloud penetration testing covers Google Cloud, AWS, and Microsoft Azure, which suits companies that grew into more than one cloud through acquisitions or separate product teams. One firm can test all three with the same method and reporting format.
Each engagement combines a configuration review with hands-on penetration testing. Testers look at identity management, network architecture, storage permissions, and how services connect, hunting for entry points that lead to overprivileged access. Engagements are objective-based, so the client can define the attack scenario that matters most, such as reaching a production database. Reports are written for both executives and engineers, with an estimate of how likely each finding is to be exploited and fix recommendations ordered by that likelihood.
4. Mandiant (Google Cloud)
Best for: enterprises that want testing shaped by Google’s own incident response work
Mandiant has been part of Google Cloud since 2022, and its consultants are known for incident response work. That frontline work feeds its cloud penetration testing. Testers simulate attacks in the client’s environment that mirror attacker behavior seen in recent Mandiant incident response investigations, and the service covers Google Cloud as well as AWS and Azure.
For a large company already committed to Google Cloud, that combination is the main draw: the people testing your setup also see how real intruders move through cloud environments. Deliverables include a high-level executive summary, technical documentation detailed enough to recreate each finding, a risk analysis, and tactical recommendations for immediate fixes. Mandiant’s wider offensive security consulting also covers web and mobile apps, embedded devices, and industrial control systems.
5. GuidePoint Security
Best for: mid-size and large companies that want cloud testing from the same partner that handles their wider security program
GuidePoint Security was founded in 2011 and is headquartered in Reston, Virginia. Cloud penetration testing sits inside its Threat & Attack Simulation practice, alongside network testing, red and purple teaming, and social engineering. Its cloud testing looks for misconfigurations, overly permissive access, and data exposure across AWS, Azure, and GCP, using real-world attack simulation to confirm which issues an attacker could really exploit.
The broader company is a security consultancy and reseller, so the same partner can help pick and deploy the tools that fix what the test finds. For a company with a lean security team and several vendors to manage, keeping testing and follow-up work under one contract can simplify things.
How to Choose a GCP Pentest Partner
Two firms can both list “Google Cloud” and run very different tests. Use these points to compare the shortlist:
| Criteria | What to look for |
| Starting access | Whether testers begin from an assumed foothold (a low-privilege account or a service account key), from the outside, or both. An authenticated start covers far more of the cloud in the same number of days. |
| IAM depth | Whether the firm tests privilege escalation for every identity, including service accounts, and across projects and folders. |
| GKE and serverless | Whether Kubernetes clusters, Cloud Run, and Cloud Functions are in scope, if your product uses them. |
| App and cloud together | Whether the same team can test the app and the GCP project behind it, so findings connect from front end to data. |
| Who tests | Named, senior testers with hands-on certifications such as OSCP. |
| Retesting | Whether a retest is included, how long the window stays open, and whether you get an updated report. CYBRI’s guide to retesting explains how this usually works. |
| Reporting | An executive summary, severity scores, GCP-specific fix steps, and mapping to SOC 2, ISO 27001, or PCI DSS. Compare samples with this checklist of what a pentest report should contain. |
Final Thoughts
Each of these five firms can test a Google Cloud environment, and the right pick depends on your size, how many clouds you run, and whether you want the app tested alongside the cloud. For SaaS companies that want OSCP-certified testers working manual-first through both the product and the GCP project behind it, CYBRI is a strong fit. A short call is enough to map the projects and services in scope, so contact CYBRI to talk it through.
Frequently Asked Questions
Do I need Google’s approval before a GCP penetration test?
No. Google doesn’t require you to notify it or ask permission before testing your own Google Cloud resources. The testing has to follow Google Cloud’s Acceptable Use Policy and Terms of Service, which means no attacks on other customers and no activity that disrupts shared infrastructure. A good testing firm will build those limits into the rules of engagement.
What should I give testers before a GCP pentest?
Plan on read-only access to the projects in scope (often a dedicated account with viewer roles), a list of the projects, folders, and key services, and a test account in your app for each user role if the app is in scope too. Name one technical contact who can grant or reset access quickly. If you want to test what a leaked key could do, agree on a test service account with realistic permissions in advance.
Is a GCP pentest different from an AWS or Azure pentest?
The method is similar, while the details differ. Each cloud has its own identity system, permission model, and services, so testers need hands-on experience with the one you run. Firms that test several clouds should show GCP-specific findings in their sample reports, such as service account privilege escalation, rather than a generic cloud checklist. CYBRI’s list of AWS penetration testing providers covers the Amazon side.
Ready for a GCP Pentest?
CYBRI tests Google Cloud environments and the apps that run on them, manual-first, with OSCP-certified testers leading every project. Critical findings are flagged the same day, reports map to SOC 2, ISO 27001, PCI DSS, and HIPAA, and fixes are retested within 90 days with an updated report. Get a quote to scope a test for your GCP setup.
