Security for Fintechs and Payment Institutions

Why fintechs are a priority target and what is at stake

Fintechs and payment institutions bring together three characteristics that make them front-line targets: they move money in real time, expose public APIs to integrate partners and customers, and concentrate sensitive data — national ID numbers, banking details, transaction history and, in many cases, card data. For an attacker, that means fast monetization: a successful account takeover or an API authorization flaw can turn into a Pix transfer in seconds, before any human review.

What is at stake goes well beyond direct financial loss. A fintech lives on trust: the perception that the customer's money and data are safe. A significant incident hits three fronts at once — financial damage (fraud, chargebacks, reimbursements), regulatory exposure (the Central Bank and the ANPD may be triggered) and reputational harm, which in financial products is usually the most expensive to recover.

For founders and lean teams there is also the speed factor: the pace of shipping features (new onboarding flows, new integrations, new credit products) introduces attack surface faster than most teams can test. Security that fails to keep up with the product stops being a control and becomes debt.

Threats and vectors typical of the financial sector

The most characteristic vector for fintechs today is the API authorization flaw. BOLA (Broken Object Level Authorization, also known as IDOR) and BFLA (Broken Function Level Authorization) are, respectively, item API1 and item API5 of the OWASP API Security Top 10 (2023), precisely because financial APIs expose objects with predictable identifiers: swapping an account, transaction or document id in a request can reveal or move another customer's data. These are flaws that automated scanners do not catch and that require manual testing against business logic.

On the identity side, account takeover (ATO) is the most direct path to fraud. Credentials leaked from other services, credential stuffing attacks, SIM swap and social engineering against support let an attacker seize the legitimate account. Once inside, transaction fraud follows — including abuse of Pix flows (keys, QR codes, portability scams) and exploitation of settlement windows.

Rounding out the picture are BEC (Business Email Compromise), in which the attacker compromises corporate email to divert payments or approve fraudulent operations, and financial data leakage — whether through a misconfigured cloud bucket or an API secret exposed in a repository. Each of these vectors has a corresponding control, and the common mistake is treating security as a single layer, when the sector demands defense in depth: API, identity, transaction monitoring and response.

Regulatory requirements for the sector in Brazil

Payment institutions authorized by the Central Bank are subject to Resolution BCB No. 85/2021, which governs the cybersecurity policy and the requirements for contracting data processing, storage and cloud computing services. In practice, it requires a formal cybersecurity policy, protection and prevention controls, incident detection and response mechanisms, and specific governance for cloud use, including when the provider is located abroad.

Financial institutions follow Resolution CMN No. 4.893/2021, with analogous requirements for cybersecurity policy and cloud contracting. Both rules converge on a point founders should not ignore: the regulator expects vulnerability management and security testing processes, plus a documented, tested incident response plan with defined roles — antivirus and a firewall are not enough.

Layered on top of this are three tiers that depend on what the fintech does. If it processes, transmits or stores card data, PCI-DSS applies, with its controls for environment segregation, encryption and regular testing. If it takes part in Open Finance, API security and governance (strong authentication, consent management, mTLS, monitoring) are part of the standard itself. And cutting across everything, LGPD governs the processing of personal data, requiring adequate security measures and notification of incidents to the ANPD and to data subjects when there is relevant risk or harm.

How Decripte implements fintech security

Decripte treats fintech security as a system, not as a standalone product. The technical starting point is API and application pentesting: we manually test authorization flows (BOLA/IDOR and BFLA), authentication, transactional business logic and integration points — exactly where automated scanners fail. The result is a remediation plan prioritized by real risk, in the format both the technical team and the regulator expect.

For continuous operation, the 24x7 SOC monitors the infrastructure and the signals of fraud and transactional abuse around the clock, correlating identity, API and edge events. When something slips through, Incident Response steps in with a containment SLA of up to 1 hour — the component the Central Bank resolutions require and that many fintechs discover they lack at the worst possible moment. In parallel, Vulnerability Management keeps the discovery-and-remediation cycle running as the product evolves.

On the compliance front, Decripte structures and evidences the controls required by the Central Bank (Res. BCB No. 85/2021 and Res. CMN No. 4.893/2021), PCI-DSS, ISO 27001, SOC 2 and LGPD, connecting each requirement to a verifiable technical control — not to a document no one tests. And Edge Security (WAF and DDoS protection) defends the public APIs, which for a fintech are, at once, the product and the largest attack surface.

Where to start

The first step costs nothing and requires no card: Decripte's free Threat Management diagnostic, the Decripte Intelligence Center (decripte.com.br/intelligence-center). It monitors credential leaks tied to your company, dark web mentions and your domain's reputation — three signals that reveal, in minutes, part of your real exposure before any project.

With the diagnostic in hand, the natural progression is to prioritize according to regulatory stage and risk. Fintechs in the authorization process or already regulated usually start with API pentesting and structuring the incident response plan, because those are direct requirements. Those who already have the basics move on to the 24x7 SOC and continuous vulnerability management.

To engage pentesting, SOC or incident response, the path is decripte.io/start; to design the approach with a specialist who understands the sector's regulation, use decripte.io/contato. In both cases, the recommendation is to start with the free diagnostic — it turns the conversation from hypotheses into data.

Termos do setor

Resolution BCB No. 85/2021

A Central Bank rule governing the cybersecurity policy and the requirements for contracting data processing, storage and cloud computing by payment institutions. It requires protection, detection and incident response controls.

Resolution CMN No. 4.893/2021

A rule from the National Monetary Council establishing the cybersecurity policy and the cloud contracting requirements for financial institutions, with requirements analogous to those of Resolution BCB No. 85/2021.

BOLA / IDOR

Broken Object Level Authorization (also called IDOR) is the flaw in which an API fails to verify whether the user has permission over the requested object, allowing access to or modification of another customer's data by swapping an identifier. It is item API1 of the OWASP API Security Top 10 and one of the most critical vectors in fintechs.

PCI-DSS

Payment Card Industry Data Security Standard: a set of security requirements mandatory for organizations that process, transmit or store payment card data, including environment segregation, encryption and regular testing.

Account Takeover (ATO)

The takeover of a legitimate account by an attacker, typically via leaked credentials, credential stuffing, SIM swap or social engineering. In fintechs, it is one of the most direct paths to transaction fraud.

24x7 SOC

A Security Operations Center that monitors the infrastructure, APIs and fraud signals without interruption, correlating events to detect and escalate threats in real time, 24 hours a day, 7 days a week.

Por onde começar

1. Run the free Threat Management diagnostic at decripte.com.br/intelligence-center to map credential leakage, dark web exposure and domain reputation, no card required.
2. Inventory your APIs and transactional flows (onboarding, Pix, transfers, credit) and identify which ones expose objects with customer identifiers — the terrain of BOLA/IDOR.
3. Engage an API and application pentest with manual testing of authorization and business logic, and prioritize fixes by real risk.
4. Structure and test a formal incident response plan with roles, a containment SLA and a communication flow to the Central Bank, the ANPD and data subjects, as required by Res. BCB No. 85/2021 and LGPD.
5. Establish continuous monitoring via a 24x7 SOC covering identity, API, transaction fraud and the edge (WAF/DDoS).
6. Map your applicable compliance (Central Bank, PCI-DSS if you process cards, ISO 27001, LGPD and Open Finance standards), connecting each requirement to a verifiable technical control.
7. Deploy continuous vulnerability management to keep pace with the release of new features and integrations.
8. For paid projects, engage at decripte.io/start or talk to a specialist at decripte.io/contato.

Perguntas frequentes