Cyber Security for Financial Services: A Pen Testing Guide

Why cyber security for financial services is a regulated obligation

Cyber security for financial services is a regulated obligation because it is now a supervised expectation backed by the Financial Conduct Authority, the Prudential Regulation Authority and the Bank of England, no longer a discretionary IT concern. Penetration testing is one of the most direct ways to evidence that the required controls hold.

The FCA Handbook, through SYSC, requires firms to maintain effective systems and controls for operational risk. The operational-resilience regime now in force expects firms to identify important business services, set impact tolerances and prove they can stay within them during severe but plausible disruption, including a cyber attack.

Financial services firms also sit higher up the target list than almost any other sector. They hold money, payment credentials and dense personal data, and sit inside payment networks and supplier chains that attackers actively probe. Ransomware crews, fraud operators and state-aligned groups all view banks, payment firms, insurers, wealth managers and fintechs as high-value objectives. That combination of regulatory scrutiny and genuine threat is why a structured testing programme, rather than an occasional scan, is now the baseline expectation.

The UK regulatory landscape that drives testing

Several overlapping frameworks shape how financial services firms approach security testing. Knowing which apply to you is the first step in scoping work sensibly.

• FCA and PRA operational resilience: firms must map important business services and demonstrate, through testing and scenario work, that they can remain within impact tolerances when systems are attacked or degraded.
• SYSC systems and controls: the Handbook expects proportionate, risk-based controls and the ability to evidence they are effective, which independent penetration testing supports directly.
• CBEST and threat-led testing: the largest, systemically important firms may be subject to the Bank of England’s CBEST intelligence-led testing, while firms below that threshold are increasingly expected to run threat-led assessments proportionate to their size.
• PCI DSS: any firm that stores, processes or transmits cardholder data must meet PCI DSS, which requires internal and external penetration testing at least every 12 months and after significant change under Requirements 11.4.2 and 11.4.3.
• UK GDPR and the Data Protection Act 2018: firms must implement appropriate technical measures to protect personal data, and Article 32(1)(d) requires a process for regularly testing their effectiveness.

You rarely need to satisfy all of these at once, but most financial services firms find two or three apply simultaneously. A well-scoped penetration test can produce evidence that supports several frameworks from a single engagement. Our sector pages set out how this maps onto specific financial services use cases.

What attackers actually target in financial services

Effective cyber security for financial services starts with understanding how firms are actually compromised, because the threat profile is distinctive. Attackers are not just after disruption; they are after money and the data that unlocks it, which changes where they apply pressure.

The most common entry points we see are internet-facing applications, customer and broker portals, and the APIs that connect core banking, payment and policy systems to mobile apps and third parties. These interfaces handle authentication, balances and transactions, so flaws such as broken access control, insecure direct object references and weak transaction authorisation carry immediate financial consequences. Business logic abuse is a particular concern: an attacker who can manipulate a payment limit or bypass a maker-checker control may never trigger a traditional vulnerability alert at all.

People remain a primary route in too. Phishing and social engineering against finance, operations and support staff are used to harvest credentials and authorise fraudulent payments, while third-party and supply-chain access gives attackers a quieter path past the perimeter. A serious programme therefore looks beyond a single asset to the full spread of routes a real adversary would consider.

A penetration testing programme that fits a financial services firm

Because the sector faces a broad threat surface and several frameworks at once, the most effective approach is a layered programme rather than a single annual scan. The right mix depends on your business model, but a typical firm benefits from combining the following over a year.

• External network and infrastructure testing: validating the internet-facing perimeter that exposes your services.
• Web application and API testing: the highest-value area for most firms, covering authentication, authorisation, transaction integrity and business logic in customer portals and payment APIs.
• Mobile application testing: essential where customers bank or transact through iOS and Android apps, covering data storage, transport security and the back end.
• Internal network testing: assessing what an attacker or malicious insider could reach after an initial foothold, including lateral movement towards core systems.
• Cloud configuration review: reviewing AWS, Azure or Google Cloud estates for misconfigurations that expose data and workloads.
• Phishing and social-engineering assessment: measuring the human layer that fraud campaigns exploit, then feeding the results into targeted training.

Many firms begin with external infrastructure and their most exposed customer-facing application, then expand to internal, cloud and social-engineering testing as the programme matures. Review the full range of engagements on our services overview and decide which layers your regulatory position calls for first.

What a financial services engagement costs and how it is priced

Scope complexity sets the price, not a per-asset price list. The variables that move the figure are the number of in-scope applications and APIs, the size of the external and internal estate, whether mobile apps and cloud platforms are included, and how much business-logic testing the work demands.

A single customer portal is a contained piece of work, while a full programme spanning external, web, API, mobile, internal and cloud testing involves far more tester days.

All of our testing is delivered by senior and principal testers at a typical UK day rate of around £1,200 to £1,300, with the price driven entirely by scope measured in tester days. As a guide, a focused web and API test of a single financial services application commonly falls in the four to six day range, which at that rate equates to roughly £4,800 to £7,200, while a broader multi-layer programme is scoped as a larger body of work. We never use junior or associate testers, and we do not apply tiered rates. For how scope translates into budget, see our guide to penetration testing cost in the UK.

How EJN Labs approaches this

EJN Labs is a CREST-accredited UK penetration testing firm, and we also hold Cyber Essentials, Cyber Essentials Plus, ISO 27001 and ISO 9001 certification. For financial services that accreditation matters, because it means the way we handle your sensitive data, scope engagements and report findings is independently assessed rather than self-declared, exactly the assurance your own regulators, auditors and clients expect. Every engagement is delivered by senior and principal testers who understand both the technical attack surface and the regulatory context a financial firm works within.

Our reports serve two audiences at once: technical teams who need clear, reproducible findings and remediation guidance, and boards, auditors and regulators who need evidence that risk is understood and being managed. Pricing is fixed and scope-based, agreed before work begins, with no day-rate creep, and we include free retests so you can demonstrate to the FCA, an auditor or an enterprise client that issues have been genuinely closed. You can see how this maps to your business on our sectors overview.

Frequently Asked Questions

Does the FCA require penetration testing for financial services firms?

Not by name for every firm, but in practice yes. The FCA’s operational-resilience and SYSC expectations require firms to evidence that their security controls are effective, and penetration testing is a widely accepted way to produce that evidence for supervisors.

For systemically important firms, the Bank of England’s CBEST scheme adds formal threat-led testing on top.

How often should a financial services firm run a penetration test?

At least annually, and again after any significant change to your applications, infrastructure or cloud environment. Most UK financial services firms work to that schedule, and PCI DSS sets the same annual-plus-on-change baseline for any cardholder data environment the firm operates.

Higher-risk firms often move to a rolling programme so that different layers are assessed throughout the year rather than in one window.

What should a financial services penetration test cover?

Cover the routes your firm is actually attacked through: external infrastructure, customer-facing web and mobile applications, the APIs behind them, internal lateral movement towards core systems, cloud configuration and the human layer through phishing. A test built around those layers mirrors real adversary behaviour.

The right mix depends on your business model, your regulatory position and which assets carry the most financial and data risk.

How much does penetration testing cost for a financial services firm?

Roughly £4,800 to £7,200 for a focused web and API test of a single application, which often falls in the four to six day range at our typical UK day rate of around £1,200 to £1,300. Cost is driven by scope measured in tester days, not a fixed per-asset price.

A full multi-layer programme is scoped as larger work. See our penetration testing cost guide for detail.

Will a penetration test help with our PCI DSS and audit requirements?

Yes. A properly scoped test produces evidence that supports several frameworks at once, including PCI DSS internal and external testing, operational-resilience expectations and UK GDPR security obligations. Our reports are written for both technical teams and auditors, and we include free retests so you can demonstrate that findings have been remediated.

Strengthen your financial services security with confidence

If your firm needs to evidence resilience to the FCA, an auditor or an enterprise client, a properly scoped penetration test is the most direct way to prove your controls hold. Our CREST-certified testers will design a programme that matches your regulatory position and risk appetite without overscoping. Request a fixed-price quote through our CREST penetration testing quote form, or explore how we work with your sector on our sectors overview.