FINANCIAL FRAUD FINTECH API SNAP

Minutes of BI-FAST API fraud through a payment aggregator. No bypass, all authenticated.

Published: 2025 · DFI Digital Forensic Team

Overview

In a matter of minutes, a series of unauthorised BI-FAST transfers was processed through a payment aggregator's API integration. Every request passed authentication, and nothing in the system appeared abnormal.

DFI was appointed to find out how the investigation proved red flags and an error in code in the authentication tool. The fraud was carried out with legitimate access, and forensic analysis allowed DFI to separate the fraudulent activity from normal operations and identify where the compromise began.

Attack chain

Six steps, reconstructed from forensic evidence.

1
Access to partner credentials COMPROMISED
2
Request pattern RECONNAISSANCE
3
Test activity VALIDATED
4
Legitimate-looking requests INFILTRATION
5
Unauthorised BI-FAST transfers IMPACT
6
Funds dispersed LAUNDERED

Actor

Actor type Externally authenticated partner credentials misused, or compromised aggregator environment.
Motivation Financial: rapid cash extraction.
Capability Understanding of SNAP API specifications, capable of script-driven automation for automated batch network API requests.

TTP: how the attack worked

Mapped to MITRE ATT&CK for Enterprise, to benchmark attack-level detection coverage.

Initial Access
Recon & Config
Valid Account Abuse
Execution
Impact

IoC: what to look for

Behavioural indicators that can be turned into monitoring rules. Match to system behaviours, not just static signatures.

TRANSACTION MONITOR

A partner's API traffic shifting away from its established profile.

SESSION MONITOR

Inconsistent metadata within the same request.

TRANSACTION MONITOR

Authorisation tokens used in calls to non-partner official application user products.

SESSION MONITOR

Anomalous metadata in the request transaction.

Detailed indicators are confidential.
DIGITAL FORENSICS · INCIDENT CONSULTANCY

When the system says everything is fine, the evidence may say otherwise.

DFI investigates fraudulent activity and security incidents for banks, payment providers and financial institutions.

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