Why APIs are now the way in
A decade ago, an attacker who wanted into a Nigerian financial institution would go through the website. Today the website is often the least interesting door. Most applications now call an API client. The USSD gateway calls an API. Every aggregator, payment switch, and partner integration is another set of endpoints, each one accepting requests from outside your network, around the clock.
Open banking widens this surface deliberately. The CBN's open banking guidelines expect banks to expose customer-permissioned account and payment services to licensed third parties through standard interfaces. That is good for competition and uncomfortable for anyone who still assumes the security perimeter ends at the login page. Each published endpoint is a potential entry point, and doors can be abused.
The flaws that matter are rarely exotic. An endpoint that returns another customer's record when one digit changes in the request, a transfer request that does not check the acount to be debited belongs to the caller. Nothing in these requests is 'malformed' per say, so scanners would not flag them as issues. Finding issues like this takes human-led penetration testing by people who read an API the way an attacker does. AI helps correlate endpoints, parameters, and repeated response patterns across a large API environment. Our senior penetration testers use those leads to test authorization and business rules directly, then verify the impact by hand.
