Account Takeover Fraud Prevention in Accounts Payable

Account takeover fraud — ATO — involves an attacker gaining unauthorized access to a legitimate account and using that access to commit fraud. In the AP context, ATO takes two forms: taking over a vendor's account to send fraudulent payment instructions, or taking over an internal AP team member's account to authorize fraudulent payments. Both are increasingly common, and both are increasingly difficult to detect because the fraud originates from legitimate, authenticated accounts.

Account takeover has accelerated AP fraud sophistication. When a fraudster sends a payment instruction from a vendor's compromised email account — not a spoofed domain, but the actual account — every technical email security check passes. The fraud looks identical to a legitimate communication.

How Account Takeover Targets AP

Vendor email account compromise. The attacker gains access to a vendor's email account through phishing, credential stuffing, or purchased credentials from a prior data breach. Once inside the vendor's inbox, they monitor communications to understand the payment relationship, timing, and amounts. When the moment is right — before a large payment run — they send a bank account change request from the genuine vendor address. The AP team has no reason to question an email from an account they've corresponded with for years.

This is Vendor Email Compromise (VEC) — and it now accounts for 61% of all BEC attacks (Abnormal AI 2026 Attack Landscape Report). The shift from spoofed domains to compromised accounts is the most significant change in AP fraud in recent years.

AP staff account compromise. The attacker targets an internal AP team member rather than an external vendor. Through phishing or credential theft, they gain access to the AP team member's email and, potentially, the organization's AP system. They use this access to approve fraudulent invoices, change vendor banking details, or authorize payment runs to fraudulent accounts — all from a legitimate internal account.

Finance system credential theft. For organizations using cloud AP platforms (BILL, Tipalti, NetSuite, QuickBooks Online), credential theft targeting AP platform logins allows attackers to directly manipulate vendor records and payment queues from a legitimately authenticated session.

Why ATO Is Harder to Detect Than Traditional Fraud

Traditional fraud detection relies heavily on identifying anomalies that suggest an impersonator: suspicious domain names, unusual email formatting, requests that don't match established patterns. Account takeover undermines these detection signals because:

The email comes from a legitimate address with full domain authentication

The account has a real history of legitimate communication

The request may closely mirror legitimate patterns the attacker has observed by monitoring the compromised account

Security tools designed to catch spoofing and phishing don't flag messages from authenticated accounts

The result: ATO-driven payment fraud is the form most likely to pass every email security and human review check in your AP process.

How Vantirs Detects Account Takeover-Driven Payment Fraud

Since ATO fraud cannot be reliably detected at the email or identity layer, Vantirs focuses on the payment destination layer — where the fraud always leaves a verifiable signal regardless of how convincing the instruction appeared.

Payment destination verification independent of instruction source: Vantirs verifies the destination bank account against your verified vendor registry, regardless of whether the payment instruction came from a verified vendor email, an internal AP approval, or a system-generated payment run. A compromised account cannot authorize a payment to a fraudulent bank account.

Bank account change velocity monitoring: Multiple bank account change requests within a short window — a pattern consistent with a compromised vendor account working through a target list — are flagged automatically.

Behavioral anomaly detection: Payment requests that deviate from an account's established patterns — different amounts, unusual timing, new bank account formats — are flagged even when they originate from legitimate authenticated accounts.

Multi-factor verification for high-value changes: Banking detail changes for high-value vendors require confirmation through a secondary channel not connected to the potentially compromised email account.

Stop account takeover fraud from reaching your AP payments.

Book a demo → — see how Vantirs detects ATO-driven payment fraud in 30 minutes.