React Native and Flutter Penetration Testing
One codebase, two platforms, and a framework layer between your logic and the device that most mobile tests ignore. We unpack it and test both stores. CREST-certified testers, fixed price from £4,240, 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, CelloriA React Native bundle is JavaScript that can be pulled out of the package and read. A Flutter app compiles to a Dart snapshot that standard mobile tooling does not decompile, so testers who rely on the usual scripts report a clean binary and move on. We do not.
The framework is an extra layer, and it hides things from the usual tooling
The framework layer also changes where security controls live. Certificate pinning implemented in JavaScript is a different proposition from pinning in the platform network stack, and storage helpers often fall back to plain files when the secure option is unavailable.
Then the bridge. Native modules expose device capability to the framework layer, and a module that trusts its caller gives anything running inside the app access to the camera, the filesystem or the keychain.
ISO 27001, SOC 2, PCI DSS and Cyber Essentials Plus audits accept manual penetration test evidence. Scan-only evidence is generally insufficient.
CROSS-PLATFORM SPECIFICS
What We Actually Test in a Cross-Platform App
Ten test areas that apply because the app is built in React Native or Flutter rather than natively, on top of the API testing behind it. Every finding is verified, reproducible and mapped to OWASP MASVS, CWE and CVSS 3.1.
Bundle and snapshot extraction
JavaScript bundles and Dart snapshots recovered from the package, and what business logic and keys they contain.
Storage
Secure storage plugins, their fallbacks, and what ends up in plain preferences, files or caches on each platform.
Certificate pinning
Where pinning is implemented, whether it survives framework-level interception, and how the app behaves when it fails.
Native bridges and modules
Custom native modules, the capability they expose, and whether they validate the caller.
Framework and plugin versions
Known issues in the framework and in the third party plugins the app depends on.
Platform differences
Findings that only appear on one platform, including exported components on Android and extension behaviour on iOS.
Deep links
Link handling in the framework router, parameters accepted from other apps, and the flows reachable that way.
Authentication and session
Token storage, biometric gating in the plugin layer, refresh behaviour and what logout clears.
Backend API
Every endpoint the app calls, tested against each role for object level authorisation and mass assignment.
Over the air updates
Code push style mechanisms, update signing, and whether an attacker can influence what the app runs next.
METHODOLOGY
What a cross-platform mobile 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.
Live API key and backend signing secret recovered from the shipped application bundle
- Affected
- The Android release build of [redacted] taken from the public store listing, version [redacted], with the same values present in the iOS build.
- What we found
- Unpacking the package and reading the application bundle produced a working third party API key and the shared secret the backend used to sign requests. Neither was restricted by application identifier, and both were identical across the two platforms.
- Why it matters
- Anyone who downloads the app can sign their own requests to your backend and spend the third party account quota, which in this case was billed per call.
- Fix
- Move the calls behind your own backend, issue short lived per device tokens, restrict the third party key by bundle identifier and platform, and rotate both values, because a key in a published binary is already public.
Reconstructed from public research: the OWASP Mobile Application Security Verification Standard, storage and cryptography requirements on hardcoded secrets in shipped binaries.
Mobile App 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 Mobile App 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 £4,240 for a small, single-scope engagement, agreed up front. Most engagements run £5,780 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
Quote request received
We will reply within one business day with your fixed-price quote from a named CREST assessor.
Your data stays with us. No newsletter signup.
or book a 20-min scoping call first
We reply within one business day. Your data stays with us. No newsletter signup.
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 Mobile App Penetration Testing Pricing
Pricing depends on the number of platforms in scope, the size of the API surface behind the app, and how much of the logic sits on the device. The day count flexes; the included deliverables stay the same across all engagements.
3 to 5 days
Single user role, basic CRUD application, marketing website with auth. Typically 5-day engagement.
Get a fixed quote5 to 7 days
Multi-role SaaS, business application with payment integration. Typically 8-12 day engagement.
Get a fixed quote7 to 9 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
Mobile App 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 Mobile App 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 test both iOS and Android builds?
Yes. One codebase still produces two different attack surfaces, and we report per platform where it matters.
Can you really test Flutter apps?
Yes. Dart snapshot analysis and framework-level interception are part of this engagement, and we say in the report what we recovered.
Is this cheaper than two native tests?
Usually, because the logic is shared. The device-level work still has to happen twice.
Is the API included?
Yes, by default. It is where the serious findings are.
What about Expo?
Covered, including the managed workflow and over the air updates.
Do you need the source?
No. The packaged app is enough, and source access speeds up triage.
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 cross-platform app tested properly
Send us both builds and the test accounts. You will have a fixed scope and a number within 24 hours.
