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Know Your Breach: Checkout
Nov 21, 2025 8:45:25 AM
The Target: Checkout operates checkout.com and is a global payment processing firm that provides a unified payments API, hosted payment portals, mobile SDK, and plugins to use on existing platforms.
The Take: Checkout says the threat actor, known as ShinyHunters, gained access to a third-party legacy system that had not been properly decommissioned, which held merchant data from 2020 and earlier, including internal operational documents and onboarding materials
The Vector: Upon investigation, Checkout determined that this data was obtained by the threat actor gaining unauthorized access to a legacy third-party cloud file storage system, used in 2020 and prior years.
This breach highlights the extreme importance of timely software updates for known software vulnerabilities, not only in systems directly under a firm’s control, but in third-party systems the firm relies upon as well. The longer a firm, or its vendors, hold out on deploying the most up-to-date software for their systems, the greater the chance an attacker will exploit the issue.
