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Hackers gained unauthorized access to firewall configuration backup files stored in SonicWall’s MySonicWall cloud backup service, impacting all users of the platform. The breach was initially disclosed in September 2025, when SonicWall urged customers to reset credentials after discovering that backup files tied to MySonicWall accounts had been exposed. Although SonicWall’s initial advisory suggested that under 5% of customers were affected, subsequent investigation confirmed that all customers using the cloud backup service were impacted. The stolen configuration files contain sensitive information, including encrypted credentials, user and group settings, DNS and log settings, and certificates, which could be leveraged by threat actors to compromise organizational networks. Only Gen 7 and newer SonicWall firewalls encrypt credentials and secrets in exported configuration files using AES-256, leaving older devices more vulnerable to exploitation. SonicWall has blocked further unauthorized access and is collaborating with cybersecurity experts and law enforcement to assess the full scope of the incident. The company has notified affected customers and provided detailed instructions for identifying impacted devices and remediating the risk. Customers are advised to import new preference files, a process that disrupts IPSec VPNs, TOTP bindings, and user access, requiring reconfiguration of VPN pre-shared keys and reset of TOTP and user passwords. To minimize operational impact, SonicWall recommends performing these actions during maintenance windows or periods of low activity, as the process necessitates an immediate firewall reboot. Arctic Wolf notes that threat actors, including nation-state and ransomware groups, have previously exploited exfiltrated firewall configuration files in subsequent attacks. SonicWall has established a dedicated support team to assist organizations with remediation and has published an in-depth advisory with up-to-date guidance. Organizations are strongly urged to reset credentials on all affected firewalls and to follow SonicWall’s recommendations to prevent unauthorized access. The exposure of these configuration files represents a significant risk, as they can provide attackers with the information needed to bypass network defenses. The incident underscores the importance of robust encryption for sensitive configuration data and the need for rapid response to cloud service breaches. SonicWall continues to work with partners and customers to ensure all affected systems are secured and to prevent further exploitation of the stolen data.
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Following the broader impact disclosure, SonicWall warned customers to treat the incident as a security risk and to rotate passwords, keys, certificates, and other secrets associated with affected firewall configurations. The company also said it was working with Mandiant and implementing additional security measures and customer support tools.
After expanding its investigation, SonicWall revised its initial assessment and said the breach impacted 100% of customers using the cloud backup service, not a smaller subset previously believed. Reports said the exposed data included firewall configuration backup files and encrypted credentials that could aid follow-on attacks.
SonicWall announced it had investigated a security incident affecting MySonicWall firewall configuration backup files stored in its cloud backup service. The company said attackers had accessed customer backup data and began notifying affected users and publishing remediation guidance.
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SonicWall confirmed that a cybercriminal accessed its MySonicWall.com portal via brute-force attacks, exposing backup firewall configuration files for less than 5% of its install base. The exposed files, while containing encrypted passwords, also included sensitive configuration data that could aid attackers in exploiting affected firewalls. SonicWall has disabled the backup feature, notified impacted customers, and advised credential resets and increased monitoring.
Jun 29, 2026
SonicWall experienced a significant security incident in early October 2025, resulting in the unauthorized access of firewall configuration backup files for all customers utilizing the MySonicWall cloud backup service. The breach exposed sensitive configuration data, including device settings, encrypted credentials, VPN configurations, private keys, and administrator information. Although the credentials and secrets were protected with AES-256 encryption, the exposure of this data raised substantial concerns about the potential for further exploitation, especially in cases where weak or reused passwords were present. Forensic analysis conducted by SonicWall in collaboration with Mandiant confirmed that 100% of cloud backup customers were affected, making this a global event with far-reaching implications for network security. Following the breach, security researchers, including those at Huntress, observed a marked increase in SonicWall SSLVPN account compromises starting on October 4, 2025. Over 100 accounts across 16 customer environments were breached, with attackers using valid credentials rather than brute-force methods. The malicious activity was traced to a single IP address (202.155.8[.]73), and attackers were seen rapidly authenticating, conducting network scans, and attempting lateral movement within affected environments. In some cases, attackers disconnected quickly, but in others, they pursued deeper access by targeting local Windows accounts. Evidence suggests that the Akira ransomware group may be leveraging both the stolen credentials and known SSLVPN vulnerabilities to facilitate these intrusions. While Huntress did not find direct evidence linking the observed SSLVPN compromises to the configuration file breach, the timing and nature of the attacks have raised concerns about a possible connection. The exposed configuration files, even though encrypted, could potentially be decoded by determined attackers, revealing authentication passwords and keys in their encrypted form. This scenario underscores the risk posed by the breach, particularly if attackers are able to crack or otherwise obtain the necessary decryption keys. SonicWall and security vendors have issued urgent guidance to affected customers, recommending immediate review of the MySonicWall portal for impact assessment and the implementation of enhanced security measures. System administrators are advised to follow SonicWall’s security checklist, which includes steps such as resetting credentials, reviewing access logs, and applying any available patches or mitigations. The incident has prompted widespread concern within the security community due to the scale of the exposure and the potential for further exploitation. The breach highlights the critical importance of strong encryption, robust credential management, and rapid incident response in cloud-based security services. It also demonstrates the potential for configuration data leaks to serve as a springboard for targeted attacks, including ransomware campaigns. Organizations using SonicWall products are urged to remain vigilant, monitor for signs of compromise, and coordinate closely with SonicWall and their security partners to mitigate ongoing risks. The incident serves as a stark reminder of the evolving threat landscape facing managed security service providers and their customers.
Jun 29, 2026
SonicWall confirmed that a security breach in September resulted in unauthorized access to firewall configuration backup files stored in certain MySonicWall accounts. The company, with support from Mandiant, determined that the attack was carried out by a state-sponsored threat actor and was limited to a specific cloud environment accessed via an API call. The breach did not impact SonicWall products, firmware, source code, or customer networks, but exposed sensitive information such as access credentials and tokens, prompting SonicWall to advise customers to reset passwords and shared secrets for various services and interfaces. Following the incident, SonicWall notified all customers using its cloud backup service for firewall configurations and provided assessment tools to help identify affected devices. The company emphasized that the breach was unrelated to Akira ransomware or other ongoing attacks and has since implemented additional security measures based on Mandiant's recommendations. Law enforcement and external cybersecurity experts were engaged throughout the investigation, and SonicWall continues to strengthen its systems to prevent future incidents involving nation-state actors.
Jun 29, 2026