Ransomware at Bank Vendor Marquis Exposes Data of 672,000 Customers

A Texas-based fintech contractor called Marquis, which provides data analytics services to hundreds of U.S. banks, says a ransomware attack on its systems in August 2025 exposed highly sensitive personal and financial data for at least 672,075 people, more than half of them in Texas. The stolen information includes names, dates of birth, addresses, bank account details, debit and credit card numbers and Social Security numbers — enough for criminals to open accounts, take out loans or impersonate victims. Marquis has sued its firewall provider, SonicWall, alleging a flaw in SonicWall’s cloud backup service let attackers obtain firewall configuration files, encrypted credentials and detailed network-architecture data that effectively gave them a blueprint to penetrate Marquis’ network and deploy ransomware. The complaint further claims SonicWall knew its backup service had been compromised earlier in the year but initially downplayed the impact, delaying Marquis’ ability to protect its systems. A Marquis spokesperson says the company took affected systems offline, hired outside cybersecurity experts and notified law enforcement, but customers are only now learning that a little-known third-party vendor, not their bank itself, was holding such sensitive data. The case underscores how hidden fintech suppliers have become a soft underbelly in U.S. banking security and is likely to fuel pressure for tougher oversight of financial-sector vendors and clearer breach disclosure to consumers.