- SonicWall confirms state-sponsored actor accessed cloud backups via API in a targeted breach
- Initially downplayed, the breach ultimately affected all SonicWall customers globally
- No product or firmware compromise occurred; Mandiant is assisting with remediation and hardening
SonicWall has blamed “state-sponsored threat actors” for the cloud backup security breach which hit its services in September 2025.
In an update posted on the company’s website, SonicWall said it completed the investigation into the incident, and confirmed that the malicious activity was “carried out by a state-sponsored threat actor” and was “isolated to the unauthorized access of cloud backup files from a specific cloud environment using an API call.”
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. This tool allows SonicWall firewall users (typically businesses and IT teams) 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).
Acting like hacktivists
At first, SonicWall said that fewer than 5% of its customer base was affected, but later confirmed the breach had impacted all of its customers (which could be as many as 500,000 around the world).
The company confirmed its products and firmware were not compromised, and that no other systems or tools, source code, or customer networks were disrupted or otherwise tampered with.
“SonicWall has taken all current remediation actions recommended by Mandiant and will continue working with Mandiant and other third parties for ongoing hardening of our network and cloud infrastructure,” it said.
In theory, the attackers could brute-force or decrypt the secrets stolen from the backup, extract credentials used in services tied to the firewall, understand network topology and rules – bypassing defenses more easily, and launch targeted attacks using insider knowledge on how the firewalls are configured.
SonicWall did not name the attackers, and so far no one has claimed responsibility for the attack. It was just stressed that these incidents are unrelated to the recent Akira attacks that also targeted backups.
Via BleepingComputer
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