Industry · Fintech & payments
Ship payment features fast without leaving the API door open
I review your APIs, wallet app and release process the way an attacker would, then tell you plainly which few fixes matter before the next launch.
- Top priorityAPI securityEvery product feature is an API call, and a logic flaw moves real money.
- Top priorityVulnerabilities & exposureFast releases and open-source packages outpace annual penetration tests.
- Top priorityMobile appsWallet apps run on phones you do not control and hold the keys to funds.
- ElevatedEdge & WAAP
- ElevatedGovernance & maturity
- BaselineMonitoring & visibility
In short
Application security for fintech and payment companies focuses on the APIs (application programming interfaces) that move money, the wallet or payment app, and how quickly code reaches production. I check authorisation on every endpoint, business logic such as top-ups and refunds, app resilience on compromised phones, and whether security testing keeps pace with releases. The result is a short, ranked list of fixes.
Where I usually start
- Application architecture review
- Mobile app security assessment
- Fractional AppSec advisor
The pressure
What fintech & payments security teams are up against.
- Release speedWith weekly or daily releases, last year’s penetration test says little about what is live today.
- APIs are the productMerchants, partners and your own app call the same APIs, so one authorisation bug can reach everyone.
- Logic-level fraudFraudsters probe top-ups, refunds, vouchers and limits for logic flaws faster than rules can be written.
- Proof before go-liveRegulators, partner banks and card schemes ask for security evidence before launch and again at renewal.
Attack scenarios
The attacks I test your defences against.
Each scenario maps to one of the six areas, so you can see which layer should have stopped it.
Try the attack simulator- Scenario 01Bots farming referral bonusesScripted sign-ups with throwaway numbers claim cashback and referral rewards faster than reviews can catch.Edge & WAAP
- Scenario 02Top-up credited twice in a raceParallel API calls redeem the same voucher or top-up before the balance updates, crediting the wallet twice.API security
- Scenario 03Cloned wallet app shared by linkA modified copy of the app, passed around on messaging apps, captures PINs and one-time passwords.Mobile apps
- Scenario 04Secret key pushed to a public repoA developer commits a payment gateway or cloud key to a public repository, and automated scrapers find it.Vulnerabilities & exposure
Recommended
Where I would start with you.
Three engagements that fit this sector best. Each ends in a prioritised plan; delivery is your call.
- 01Application architecture reviewThreat-models a new payment or wallet platform before launch, while design changes are still cheap.1–3 weeksFixed feeSee the service
- 02Mobile app security assessmentChecks the wallet app against rooting, hooking, cloning and secrets left in the package.1–2 weeksFixed feeSee the service
- 03Fractional AppSec advisorSenior AppSec judgement every month, without hiring a full-time head of application security.MonthlyRetainerSee the service
Rules you work under
The frameworks I map findings to.
Findings are written so your risk, audit and compliance teams can use them directly. This is orientation, not legal advice.
- PCI Security Standards CouncilPayment Card Industry Data Security Standard (PCI DSS) v4.0.1Payment flows, card vaults and checkout scripts are all in scope, so app changes need security review before release.
- Parliament of Sri LankaPersonal Data Protection Act, No. 9 of 2022Wallet and lending apps collect identity and transaction data, which this Act protects in Sri Lanka.
- Saudi Data and Artificial Intelligence AuthorityPersonal Data Protection LawGoverns personal data processed in Saudi Arabia, including conditions on sending it abroad, which shapes API design.
- ISO and IECISO/IEC 27001:2022A common ask from partner banks and enterprise clients. Its secure development controls only help if releases follow them.
Proof
Programmes I have led, and why they transfer.
My delivery work so far has been in banking and a global group. The controls, failure modes and lessons carry straight across to fintech & payments.
- 112applications migrated112 bank applications moved to cloud WAAP, wave by waveBanking · A leading Sri Lankan private bankF5 Distributed CloudRead the case
- 120applications protectedAround 120 applications under WAAP, API and bot protectionManufacturing · A global apparel group headquartered in Sri LankaImpervaRead the case
- T1bank vulnerability programmeTier-1 bank scanning upgraded and extended to web applicationsBanking · A Tier-1 Sri Lankan commercial bankTenable Security CenterRead the case
- RASPin-app protection liveIn-app runtime protection live in a customer banking appBanking · A leading private bank’s mobile appZimperiumRead the case
Where I work with fintech & payments teams
What should a fintech fix first in application security?
Start with authorisation on the APIs (application programming interfaces) that move money or expose customer data: every request should check that the caller owns the account, wallet or transaction it names. Next, test business logic such as top-ups, refunds and limits for race conditions and replays. Then look at the mobile app and at secrets in code. Those three areas usually carry the most early risk.
Is a yearly penetration test enough for a fintech that releases every week?
Rarely. A yearly test shows one version of an application that may have changed many times since. A better pattern combines automated checks in the build pipeline, such as SAST (static application security testing) and dependency scanning, with focused manual testing whenever money flows, authentication or integrations change. The yearly test then checks the process rather than being the only control.
Does PCI DSS apply to a fintech?
If you store, process or transmit card data, or can affect the security of systems that do, PCI DSS (Payment Card Industry Data Security Standard) applies, usually through your acquirer or payment partner. A hosted payment page or tokenisation can shrink the scope a lot, but the pages and scripts around it still need protecting. I assess the application side; formal validation follows your acquirer’s process.
Can you review our platform before it launches?
Yes. An application architecture review looks at one platform end to end: how clients authenticate, how APIs (application programming interfaces) authorise each request, where secrets live, what sits at the edge and what gets logged. You get a threat model and a short, ranked list of design changes. Fixing these on paper costs far less than fixing them after customers and partners depend on the platform.
We have no head of application security. How can you help?
A fractional arrangement gives you senior application security guidance on a monthly retainer: reviewing designs and vendor choices, keeping the security roadmap moving, and being on hand for escalations when something goes wrong. It usually follows an assessment, so the work starts from evidence rather than opinion. It suits teams that are growing faster than they can hire.
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