Introduction

Failed Card Verification Number (CVN) transactions can indicate potential fraud activity, especially when linked to automated card testing attacks. Fraudsters frequently use botnets to test stolen card credentials at high velocity, submitting rapid sequences of small or low‑value transactions to identify valid cards. Merchants can significantly reduce failed CVN attempts by implementing controls that detect abnormal behavior and prevent automated attacks.

Overview

This article provides recommended steps to mitigate failed CVN attempts and reduce exposure to card testing fraud. It includes best practices for checkout security, velocity and anomaly controls, and references to CyberSource fraud prevention products designed to help merchants detect and block high‑risk activity.

Recommended Actions to Reduce Failed CVN Attempts

• Implement bot and automation defenses: Use CAPTCHA, firewalls, device fingerprinting, proxy‑piercing technologies, and other bot‑mitigation tools to block automated scripts from submitting transactions.
• Enable velocity controls: Configure limits around repeated attempts from the same device, IP address, payment card, email, or customer profile. Sudden spikes in CVN failures are often an early indicator of card testing activity.
• Set minimum transaction amounts: Donation flows or free‑text payment fields are frequently targeted because fraudsters can test cards with very low values. Minimum thresholds help expose testing behaviors earlier.
• Monitor for anomalies: Regularly review transaction patterns to identify unusual CVN failure rates or repeated low‑value authorizations.

Fraud Management Tools to Assist

CyberSource provides fraud‑prevention solutions that can help reduce CVN failures and guard against card testing attacks:

• Fraud Management Essentials (FME)
  Designed for small to mid‑size businesses, FME includes automated rules, screening, and velocity checks to help detect and prevent high‑risk transactions.
• Decision Manager (DM)
  Provides advanced fraud detection capabilities including device fingerprinting, machine learning, risk indicators, and configurable velocity rules, making it highly effective at identifying card testing behavior.

Additional Guidance

For more detailed strategies to prevent card testing and CVN‑related fraud, see: 3 Steps for Protecting Your Business from Card Testing Attacks

Velocity definition: The 'velocity check', sometimes referred to simply as 'velocity', is a feature of the Advanced Fraud Screen service that allows merchants to monitor the rate of transactions with repeating information sent in by the end-user.  This information may then be used to trigger a review or rejection of potentially a fraudulent order when repeated past a desired threshold.