Marquis Software Solutions is suing SonicWall for gross negligence and misrepresentation following a ransomware attack that impacted 74 American banks. The lawsuit claims that a security gap in SonicWall's cloud backup service allowed state-sponsored hackers to bypass security measures and steal sensitive data from Marquis's network.
Marquis Software Solutions has initiated legal action against cybersecurity firm SonicWall, alleging that the vendor's failures led to a devastating ransomware attack in August 2025. The breach resulted in the theft of personal and financial data belonging to customers of dozens of banks that rely on Marquis for data analytics and compliance services. While it was initially believed that the hackers exploited an unpatched flaw, subsequent investigations revealed a much deeper issue within SonicWall’s own infrastructure.
The core of the complaint centers on a security vulnerability introduced by SonicWall in February 2025 through an API code change in its MySonicWall cloud backup service. This error allowed unauthorized access to sensitive firewall configuration files, which contained encrypted credentials and multi-factor authentication scratch codes. Marquis asserts that although its own systems were fully updated and protected by multi-factor authentication, the attackers were able to bypass these defenses using information stolen directly from SonicWall’s cloud.
Evidence from an investigation by Mandiant indicated that the breach was the work of state-sponsored hackers. Marquis claims that SonicWall was not transparent about the scope of the issue, initially downplaying the number of affected customers before eventually admitting that its entire client base was impacted. Furthermore, Marquis alleges that when it sought technical answers regarding the bypass of its security protocols, SonicWall ignored the inquiries and withheld critical information regarding the vulnerability.
The fallout from the cyberattack has been extensive, with Marquis reporting significant damage to its business reputation and a loss of enterprise value. The company is currently defending itself against more than 36 consumer class action lawsuits filed by individuals whose personal information, including Social Security numbers and financial details, was compromised during the breach. These legal challenges have placed a massive financial and operational strain on the organization.
In its lawsuit, Marquis is seeking comprehensive monetary damages and indemnification to cover the costs of the ongoing class action litigation. The company argues that SonicWall’s misrepresentations and negligence are directly responsible for the breach and the subsequent loss of business opportunities. The legal battle highlights the growing tension between software service providers and cybersecurity vendors when cloud-based vulnerabilities lead to downstream disasters for financial institutions.
Source: Marquis Files Lawsuit Against SonicWall After Backup Breach Sparks Ransomware Attack