Expanding API and IoT integration increases risk because it widens the attack surface and connects banks to devices and partners that may not support the security controls financial services require. More connections also mean more data flows, more trust dependencies, and more places where weak authentication, poor configuration, or unmanaged third parties can expose systems. Security has to scale with integration, not follow it later.
Why API and IoT integration raises the banking attack surface
APIs and connected devices expand the number of externally reachable paths into financial systems, which changes the problem from protecting a smaller set of core applications to protecting many more entry points, protocols, and trust relationships. That matters because attackers do not need to defeat the strongest control everywhere, they only need one weak integration, exposed endpoint, or overlooked dependency to reach sensitive workflows.
The practical issue is not just volume, but diversity. API gateways, partner interfaces, mobile apps, smart devices, sensors, and middleware each introduce different authentication patterns, data formats, and failure modes, so uniform control is harder to enforce. A bank may have mature controls around its core ledger and still inherit exposure through a less mature integration path.
For API-specific exposure, the most common risk is that the integration layer becomes the easiest place to abuse authorization, inventory, and consumption limits. The OWASP API Security Top 10 is useful here because it frames the control failures that matter most when business logic is exposed through APIs, especially broken authorization and misconfiguration: OWASP API Security Top 10.
Why third-party and device trust makes the risk harder to contain
Integration increases risk because it extends the bank’s trusted perimeter beyond systems it directly owns and operates. Third-party platforms, device vendors, firmware, customer-owned endpoints, and embedded services may not follow the same patching cadence, logging discipline, or configuration standards, yet they can still carry authenticated access into banking workflows.
IoT also tends to create long-lived trust relationships. Devices are often deployed at scale, remain in service for years, and are difficult to rotate, re-enroll, or replace quickly. If a device identity, API key, certificate, or partner credential is exposed, the resulting access can persist far longer than the business expects, especially when lifecycle control is weaker than application security control.
That is why integration risk is also a dependency risk. The bank does not only own its own code path, it also depends on the security posture of devices, suppliers, and integration partners. When that dependency is weak, compromise can enter through a path that looks operational rather than obviously hostile. This is the same basic failure pattern highlighted by modern guidance on third-party exposure and product hardening, including CISA Secure by Design.
Where the integration connects to critical infrastructure, industrial telemetry, or operational systems, the exposure is even broader because availability and integrity become part of the security problem, not just confidentiality. Banks that touch such environments should treat the integration boundary as a control zone, not a convenience layer.
Why integration failures become governance and resilience failures
As integration grows, security failure is less likely to be a single technical flaw and more likely to be a governance gap: missing ownership, incomplete inventories, weak exception handling, or unclear responsibility for who can approve, revoke, monitor, and test the connection. The larger the integration estate, the easier it is for risky connections to persist without a clear business owner.
Resilience also suffers when banks cannot see or quickly isolate which integrations are critical. If a partner API or connected device starts failing or is suspected of compromise, the bank may have to choose between shutting down a business channel or leaving an unsafe pathway live. That trade-off is especially severe in finance because service continuity and fraud prevention both matter at once.
For financial institutions, operational resilience frameworks are directly relevant because they require institutions to understand third-party dependencies, test critical services, and manage ICT risk as a business continuity issue as much as a cybersecurity one. DORA is the clearest regulatory example in this space: EU Digital Operational Resilience Act (DORA).
Risk and Threat Considerations
Expanded API and IoT integration creates a larger attack surface, but the deeper risk is that attackers can exploit the least mature trust relationship rather than the most valuable system. Weak authentication, exposed secrets, permissive partner access, and unmanaged devices can all become entry points for data theft, fraud, or lateral movement into higher-value banking systems.
Failure mechanism: A poorly governed integration exposes credentials, accepts excessive trust from a partner or device, or lacks sufficient monitoring, allowing an attacker to authenticate legitimately and move through connected workflows without triggering immediate suspicion.
Impact: The result can be unauthorized access, manipulation of transactions or device data, broader compromise of internal systems, and a much larger incident response scope because the bank must investigate both its own environment and every connected dependency.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP API Security Top 10 addresses the attack surface, CIS Controls v8 and NIST CSF 2.0 set the technical controls, and DORA and ISO/IEC 27001:2022 define the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP API Security Top 10 | API5 — Broken Function Level Authorization | API integrations expose banking functions to authorization abuse. |
| API8 — Security Misconfiguration | Integration sprawl increases misconfiguration and trust-boundary mistakes. | |
| API9 — Improper Inventory Management | More integrations require complete visibility into exposed APIs. | |
| Recommendation — Enforce function-level authorization on every exposed API action. Harden API deployment defaults and continuously review configuration drift. Maintain an authoritative inventory of all production APIs and consumers. | ||
| CIS Controls v8 | CIS-5 — Account Management | Integration risk depends on controlling partner, service, and device access. |
| CIS-15 — Service Provider Management | Third-party integrations create supply-chain and trust dependency risk. | |
| Recommendation — Restrict and regularly review all non-human and third-party access paths. Assess and govern each external provider before granting production connectivity. | ||
| NIST CSF 2.0 | GV.SC-01 — Cyber Supply Chain Risk Management | Banks inherit risk from external devices, vendors, and integration partners. |
| PR.AA-01 — Identities and Credentials are Issued, Managed, Verified, Revoked and Audited | Expanded integrations depend on stronger credential lifecycle control. | |
| ID.AM-01 — Physical Devices and Systems Are Inventoried | IoT integration risk rises when connected assets are not fully inventoried. | |
| Recommendation — Map and govern supplier-related cybersecurity obligations for every integration. Manage credentials and identities with full lifecycle controls across integrations. Keep an accurate inventory of connected devices and integration endpoints. | ||
| DORA | ICT third-party risk management | Financial institutions must govern outsourced and connected ICT dependencies. |
| Recommendation — Apply formal third-party risk controls to every material integration. | ||
| ISO/IEC 27001:2022 | A.5.19 — Information security in supplier relationships | External APIs and IoT links are supplier-dependent security relationships. |
| Recommendation — Set security requirements and monitoring expectations for suppliers. | ||
Practitioner Guidance
What to prioritise: Treat every new API or IoT connection as a risk acceptance decision, not a technical onboarding task. If the integration can reach sensitive data or payment-adjacent workflows, require explicit ownership, revocation paths, and monitoring before production exposure.
What to verify: Confirm that each integration has strong authentication, constrained authorization, a current inventory entry, and a defined offboarding process. The common mistake is to secure the core application while leaving partner tokens, device credentials, and backend service accounts with longer-lived access than the business intended.
Practitioner takeaway: Integration risk is mostly a control-scaling problem, the institution’s security posture must scale at the same pace as connectivity, or the weakest external trust path becomes the effective perimeter.
Related resources from NHI Mgmt Group
- Why does an expanding attack surface increase operational and financial risk for organisations?
- How should financial institutions apply NYDFS cybersecurity requirements to API assets?
- Why does weak beneficial ownership transparency increase money laundering risk for financial institutions?
- Why does weak data management increase DORA compliance risk for financial institutions?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 26, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
