Marquis, a Texas-based financial services provider, revealed this week that a ransomware gang stole the data of over 670,000 individuals in an August 2025 cyberattack that also disrupted operations at 74 banks across the United States.

The company provides digital marketing, data analytics, compliance, and CRM services to more than 700 banks, credit unions, and mortgage lenders across the United States.

In data breach notifications filed with U.S. Attorney General offices in early December, Marquis said it suffered a ransomware attack on August 14, 2025, after the threat actors compromised a SonicWall firewall.

After breaching its network, the attackers stole a wide range of personal and financial information, including affected individuals' names, dates of birth, addresses, phone numbers, Social Security numbers, Taxpayer Identification Numbers, and financial account information without security or access codes.

"The incident was limited to Marquis’s systems and did not affect our customer’s systems," the fintech company said in data breach notification letters sent to 672,075 affected people this week.

"Our customer reviewed the affected files on December 10, 2025, and afterwards worked to validate and identify individuals whose information may have been affected by the incident, and our customer worked as quickly as possible to obtain individuals’ most recent mailing address information."

In January, Marquis blamed the ransomware attack on a security breach disclosed by SonicWall on September 17, when the company warned customers to reset their MySonicWall account credentials.

At the time, SonicWall said the incident affected only about 5% of its firewall customers using its cloud backup service and warned that the attackers could extract access credentials and tokens, which would make it "significantly easier" to compromise affected customers' firewalls.

A Mandiant investigation into the September attack also found evidence linking the incident to a state-sponsored hacking group. 

In February, Marquis filed a lawsuit against SonicWall, accusing the cybersecurity company of gross negligence and misrepresentation, which allegedly led to the ransomware attack on the fintech firm's systems in August 2025.

"As a result of SonicWall’s conduct, Marquis has suffered, and continues to suffer, damages; a loss of customers; harm to its business reputation; lost business opportunities, revenue and profit; and substantial diminution in its enterprise value," Marquis noted in the complaint.

The company also noted that it was defending over 36 consumer class action lawsuits stemming from the August 2025 cyberattack and the resulting data breach, and it was seeking monetary damages, indemnification, contribution for any judgments in the related class actions, attorneys’ fees, and equitable relief.