What happens when online merchants do not use extra authentication for suspicious purchases?

Without step up authentication, merchants are more likely to approve fraudulent orders that later turn into chargebacks. The business absorbs payment disputes, loses merchandise, and may also damage customer trust if stolen cards are used repeatedly. Over time, weak authentication makes it easier for criminals to validate stolen details and scale abuse across multiple accounts.

Why suspicious-order step up authentication changes the fraud outcome

Suspicious purchases are not just a screening problem, they are an authorization problem. step up authentication adds a stronger proof step when the order looks risky, which can stop a stolen card or compromised account from being used successfully. Without it, merchants rely on weaker signals alone, so fraudsters have a much easier path to place orders that appear legitimate at checkout.

The key operational effect is that fraud screening becomes less selective. A low-friction checkout is good for conversion, but when the order has clear risk indicators, failing to challenge the buyer shifts the burden from prevention to post-transaction recovery. That usually means more chargebacks, more fulfillment waste, and more manual review after the loss has already happened.

How merchant losses and customer harm show up

When extra authentication is missing, the business often pays twice: first for the product or service that is shipped, then again for the dispute process after the cardholder contests the charge. If the fraud is repetitive, the merchant can also see increased account testing, where criminals use small purchases to validate stolen payment details before scaling to larger abuse.

Customer trust can be affected as well. Legitimate buyers may see their cards flagged less often, but stolen-card purchases and account takeovers create support friction, delivery failures, and reputational damage. The practical lesson is that authentication controls are not only about stopping one bad order, they are about preserving confidence in the checkout path as a whole.

Where step up authentication fits in a broader fraud control stack

Step up authentication works best as one layer in a wider fraud strategy that also includes velocity checks, device and behavioral signals, shipping and billing consistency, and careful exception handling. It should be targeted, not universal. If the challenge is triggered too often, legitimate customers will abandon checkout; if it is triggered too rarely, high-risk orders slip through.

For merchants, the important question is not whether to challenge every buyer, but whether the challenge is applied when the risk is materially higher than normal. That means tuning for the payment method, order size, geography, account history, and delivery pattern, then measuring whether the added step reduces fraud without creating excessive friction for good customers. The related NIST SP 800-63 Digital Identity Guidelines are useful when deciding how much assurance a stronger check should provide, and the OWASP ASVS is a solid reference for authentication and access-control expectations in purchase flows.

Risk and Threat Considerations

Missing step up authentication creates a predictable fraud path: attackers test stolen payment data, place suspicious orders, and rely on the merchant to detect the abuse only after fulfillment or chargeback. The risk grows when weak checks are combined with high-value goods, digital delivery, or repeated account testing.

Failure mechanism: The checkout flow accepts a risky transaction without requiring a stronger proof step, so the merchant cannot distinguish a legitimate buyer from a fraudster using stolen credentials or payment details.

Impact: Fraud losses increase through chargebacks, merchandise loss, operational review costs, and repeated abuse that can degrade payment acceptance and customer trust.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

NIST SP 800-63, OWASP ASVS and CIS Controls v8 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.

Framework	Control / Reference	Relevance
NIST SP 800-63	Digital Identity Guidelines	Suspicious-order step up authentication hinges on stronger identity assurance.
Recommendation — Apply higher-assurance authentication when risky checkout signals require stronger proof.
OWASP ASVS	V6 — Authentication	Checkout step up is an authentication control for risky purchase flows.
	V8 — Authorization	Risk-based purchase approval depends on enforcing who may complete the transaction.
Recommendation — Require stronger authentication for suspicious transactions before order acceptance. Enforce stricter authorization checks when purchase risk indicators are elevated.
ISO/IEC 27001:2022	A.5.15 — Access control	Risk-based purchase approval is an access-control decision over transaction completion.
Recommendation — Tighten access-control decisions for checkout paths that show fraud indicators.
CIS Controls v8	CIS-6 — Access Control Management	Suspicious-order handling needs stronger control over who can complete purchases.
Recommendation — Restrict transaction completion when fraud signals indicate elevated purchase risk.

Practitioner Guidance

What to verify: Confirm that the challenge is driven by risk signals, not just by order value or a fixed rule. The best programs validate that high-risk patterns, such as mismatched geography, abnormal velocity, and account anomalies, are what trigger the extra step.

Decision rule: If the order can create immediate shipment loss or irreversible digital delivery, err toward stronger authentication before fulfillment. If the added friction meaningfully harms conversion, narrow the challenge to the riskiest segment rather than removing it entirely.

Practitioner takeaway: The goal is not maximum friction, it is maximum resistance where loss would be hardest to unwind. A good control stops fraud at the point of decision, before the merchant turns a suspicious order into a chargeback event.