Marquis confirms sensitive personal data of 672,000 people stolen in ransomware attack
The August 2025 SonicWall breach keeps getting worse
· TechRadarNews By Sead Fadilpašić published 19 March 2026
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- Marquis confirms August 2025 breach impacted 670,000+ people
- Attack tied to SonicWall MySonicWall brute-force incident exposing firewall configs
- Marquis is suing SonicWall, which disputes connection between the two events
The August 2025 cyberattack on Marquis affected more than 670,000 people, the company confirmed earlier this week.
Marquis is a US fintech company building software for banks and credit unions, and to defend its internal network, it uses a firewall built by SonicWall.
In mid-September 2025, SonicWall warned its firewall customers to reset their passwords after unnamed threat actors brute-forced their way into the company’s MySonicWall cloud service.
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Lawsuit filed
This tool allows SonicWall firewall users to back up their firewall configuration files, including network rules and access policies, VPN configurations, service credentials (LDAP, RADIUS, SNMP), or admin usernames and passwords (if stored in config).
SonicWall later confirmed that all of its customers were affected, and Marquis said it was among them.
Initially, there were no reports on the number of people affected. Marquis filed reports with multiple Attorney General’s Offices, stating that different types of information were stolen in different states. "The personal information potentially involved for Maine residents includes names, addresses, phone numbers, Social Security numbers, Taxpayer Identification Numbers, financial account information without security or access codes, and dates of birth,” it said in its Maine filing.
Now, BleepingComputer says the company confirmed more than 670,000 victims.
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