Firebase Security Review
In a Firebase app the client talks to the database directly, so your security rules are the entire access control layer. We test them the way a client would, with a real account and without one. CREST-certified testers, fixed price from £2,690, scoped in 24 hours.
- Unlimited retesting
- No rescheduling or cancellation fees
- Fixed quote within 24 hours
“I would highly recommend EJN Labs to any organisation seeking reliable, detailed, and well-managed penetration testing services, particularly for government or enterprise-level projects.”
Imran SaghirProject Lead, SquareOne“There wasn’t another company we could find that could deliver what we needed in the timeframe we needed. The client loved it, and we got instant ROI from the engagement.”
Dan WilcocksonCo-Founder, CelloriThere is no server-side controller to fall back on. The mobile or web client queries Firestore or Realtime Database directly, and the rules decide what comes back. If a rule is broader than the interface, the extra data is one query away for anyone who reads the bundle and finds the project identifier.
In Firebase, the rules file is the application security
Rules are also hard to reason about. Nested collections inherit or do not inherit depending on the path, functions inside rules are easy to write and easy to get subtly wrong, and test coverage for rules is rare in the projects we see.
Then the rest of the platform: authentication settings that allow sign-up when they should not, cloud functions callable without an auth check, storage buckets with permissive rules, and API keys in the client that are fine in principle and dangerous when a service is enabled that should not be.
ISO 27001, SOC 2, PCI DSS and Cyber Essentials Plus audits accept manual penetration test evidence. Scan-only evidence is generally insufficient.
FIREBASE SPECIFICS
What We Actually Test in a Firebase Project
Ten areas that apply because the backend is Firebase, on top of the standard application checks. Every finding is verified, reproducible and mapped to OWASP, CWE and CVSS 3.1.
Firestore rules
Every collection queried directly with an authenticated client, an unauthenticated one, and an account that should not have access.
Realtime Database rules
Path-level rules, inheritance, and data reachable by listening rather than reading.
Storage rules
Bucket and object rules, upload constraints, content type handling and public download URLs.
Authentication configuration
Providers enabled, sign-up policy, email verification, custom claims and how they are set.
Cloud functions
Callable and HTTP functions tested without authentication, argument tampering, and functions that run with admin rights.
Custom claims and roles
Where claims come from, whether a client can influence them, and what they unlock in the rules.
Client configuration
API keys and project identifiers in the bundle, which services they unlock, and App Check coverage.
Data model exposure
Documents that hold more fields than the interface shows, including internal flags and other users data.
Emulator and environment separation
Development projects with production data, and rules that differ between environments.
Quota and abuse
Unmetered reads and writes, unauthenticated function calls, and the cost of a hostile client.
METHODOLOGY
What a Firebase finding looks like
Written the way a finding appears in our reports. The example below is reconstructed from publicly documented research, with hosts, paths and identifiers redacted. We do not republish client findings, named or anonymised.
Database security rules left in test mode expose every document
- Affected
- The user and order collections on the Firebase project behind [redacted], with anonymous sign in enabled in the client.
- What we found
- The rules allowed read and write to any authenticated request, and the application allowed anonymous authentication. From a fresh anonymous session created with the configuration that ships in the web bundle, we read every order document and wrote to another user profile.
- Why it matters
- Full read of customer records and the ability to change them, reachable by anyone who opens the site and reads the client configuration, which is public by design.
- Fix
- Write rules that compare the authenticated user identifier against the document owner, deny by default, cover subcollections explicitly, and test the rules in your pipeline with the emulator rather than by hand in the console.
Reconstructed from public research: published 2024 research that identified thousands of sites exposing records through misconfigured Firebase rules, and the Firebase documentation which flags test mode rules as insecure and time limited.
Firebase Penetration Testing: From Scope to Attestation
CREST-aligned methodology built on OWASP Web Security Testing Guide, OWASP ASVS, NIST SP 800-115, and PTES. Each finding maps to all four standards plus your specific compliance regime.
Reconnaissance
Application mapping, technology fingerprinting, content discovery, parameter enumeration, authentication-flow analysis, role-matrix construction.
Vulnerability Assessment
Authenticated and unauthenticated automated scanning across every user role, plus targeted manual checks for known weakness patterns.
Manual Exploitation
Hands-on testing by a CREST-certified pentester. Business-logic exploitation, chained vulnerabilities, privilege escalation, impact validation.
Reporting + Retest
Executive summary, technical report with CVSS scores and reproduction steps, walkthrough call, free retest after remediation, attestation letter.
CREDENTIALS
Verified Accreditations Auditors Accept
Every credential below is independently verifiable. UK procurement teams, FCA supervisors, ISO 27001 / SOC 2 auditors, and cyber insurance underwriters all recognise these standards.
GET YOUR QUOTE
Get a CREST Firebase assessment pen test quote in 24 hours
A fixed-price quote back in one business day, from a named CREST assessor. No sales pipeline, no chasing.
- CREST and IASME accredited. Testing your auditors and clients already recognise.
- Fast-track testing within 24 hours where required. Free retest of every fix included.
- Live findings via your client portal, not a four-week PDF.
- Fixed price from £2,690 for a small, single-scope engagement, agreed up front. Most engagements run £4,080 and up. No day-rate surprises.
Dan WilcocksonCo-Founder, CelloriUnder NDA Further named references available on a scoping call.
- We reply within one business day with a fixed-price quote from a named CREST assessor.
- You approve the scope and we book a start date, usually within 24 hours.
- Live findings land in your client portal as we test, with a free retest of every fix.
Get your fixed pen test quote in 24 hours
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COMPLIANCE READY
Reports Mapped to Every Framework
Findings are explicitly tagged to the relevant control reference. Your audit team submits the report directly without translation work.
ISO 27001:2022
Annex A.8.8 management of technical vulnerabilities plus A.5.15-5.18 and A.8.2-8.5 access control validation.
SOC 2 Type I & II
CC6 logical access, CC7 system operations, CC8 change management evidence.
PCI DSS
Requirement 11.4 application penetration testing across cardholder data environments, including ecommerce penetration testing for online retail platforms.
FCA SYSC
SYSC 4.1.1R, 6.1.1R, 13 mapped to each finding for FCA-regulated firms.
UK GDPR
Article 32 effectiveness testing, customer-data security controls, ICO-acceptable evidence.
Cyber Essentials Plus
Direct certification through our IASME body status, single-vendor delivery.
PRICING
Transparent Firebase Penetration Testing Pricing
Pricing depends on app complexity, user-role count, business-logic depth, and integration surface. The day count flexes; the included deliverables stay the same across all engagements.
2 to 3 days
Single user role, basic CRUD application, marketing website with auth. Typically 5-day engagement.
Get a fixed quote3 to 5 days
Multi-role SaaS, business application with payment integration. Typically 8-12 day engagement.
Get a fixed quote5 to 7 days
Multi-tenant platform, complex authorisation matrix, integration-heavy applications. 15-20 day engagement.
Get a fixed quotePart of Technologies We Pen Test. These are examples of the stacks we publish pages for, not a complete list. If yours is not here we still test it. Related pages:
BY SECTOR
Firebase Penetration Testing for Your Sector
Sector-specialist scoping for UK businesses with sector-specific compliance regimes and threat models.
Fintech & FCA-Regulated
FCA SYSC, Open Banking FAPI 1.0, PSD2 SCA, payment-flow scrutiny, KYC/AML testing.
Fintech sector pageSaaS Companies
SOC 2 Type I & II evidence, multi-tenant boundaries, role escalation, customer-tenant isolation.
SaaS sector pageLaw Firms
SRA Cyber Standard, privileged data, conveyancing fraud defence, partner-tier procurement.
Law firm sector pageHealthcare
NHS DTAC, DSP Toolkit v6, UK GDPR Article 32, EHR systems, telehealth platforms.
Healthcare sector pageInsurance
FCA / PRA Operational Resilience, cyber underwriting, claims data, broker portals.
Insurance sector pagePublic Sector
CCS / G-Cloud framework, NCSC-aligned, citizen-facing services, PSN-compliance scrutiny.
Public sector pageWHY EJN LABS
What You Get From Firebase Penetration Testing
Six concrete differentiators competitors don’t all match.
CREST-Certified Testers, Verifiable
Every test by a CREST-certified pen tester (CRT, CCT APP, CCT INF where applicable). Verify our company status at crest-approved.org.
24-Hour Startup, Where Required
From signed scope to active testing in a single business day for incident response, audit deadlines, or regulator-driven timelines.
Live Findings, Not 4-Week PDFs
Critical issues reported during testing through your client portal. Your team remediates while testing continues.
Audit-Ready Reports
Executive summary plus full technical report with CVSS scores and explicit framework mappings (ISO 27001, SOC 2, PCI DSS, FCA SYSC).
Free Retests, Standard
Verify remediation of every finding before close-out. Letter of attestation for audit submission included. Most competitors charge £1,500-£3,000 per retest.
UK-Based CREST Testers
Every engagement performed by vetted, UK-based CREST-certified testers, matched to your needs, security clearance, and compliance scope.
FAQ
Frequently Asked
Do you need admin access to the project?
Read access to the rules and the configuration makes the review far more complete. We can also test purely as a client.
Is this part of the Google Cloud review?
It overlaps. The cloud review covers the project and its identity model. This covers the Firebase services your app talks to.
Can you test without the mobile app?
Yes. We can query the backend directly once we have the project configuration, which is in the app anyway.
Will testing create data in our project?
We write only where the scope allows it and we clean up. Where writes are destructive we use a staging project.
Does App Check solve this?
It raises the bar for casual abuse. It does not fix a rule that allows reading a collection.
What about the app itself?
That is the mobile or JavaScript page, and most clients scope them together.
What is included in the price?
Scoping, testing, the executive summary, the technical report, a walkthrough call and free retests until the finding is closed. One scope, one number, no follow-up invoices.
How fast can you start?
Scope to active testing in 24 hours once the scope is agreed, subject to tester availability in your window.
Are your testers CREST certified?
Yes. EJN Labs is a CREST member company and testing is delivered by CREST-qualified testers. The membership is verifiable on the CREST marketplace.
20+ CREST-accredited testing services in one place
Web, mobile, API, cloud, AI, infrastructure, red team. Pick the test that fits your environment.
Get your Firebase rules tested properly
Send us the project configuration and a test account. You will have a fixed scope and a number within 24 hours.
