SonicWall Gets Torpedoed: Breach of Cloud Firewall Backups
- Javier Conejo del Cerro
- 19 sept
- 4 Min. de lectura
SonicWall, long considered one of the cornerstones of network defense, faced a direct hit when attackers launched a brute-force campaign against MySonicWall accounts. The intrusion gave threat actors access to firewall cloud backup preference files affecting fewer than 5% of customers. Though the number may seem small, the significance is not: the stolen files contained encrypted credentials and critical configuration details that adversaries could leverage to map defenses, identify weak points, and prepare follow-on exploitation. SonicWall emphasized this was not a ransomware event, but rather a methodical brute-force infiltration of accounts, revealing the fragility of security even in companies whose mission is to protect others.
Phase 1: Under Fire – Brute-Force Campaigns
The attackers didn’t rely on zero-days or stealthy implants to breach SonicWall’s walls. Instead, they used persistence and automation. The campaign revolved around three main brute-force techniques:
Credential stuffing – attackers fed MySonicWall login portals with usernames and passwords leaked from unrelated breaches, hoping that customers reused their credentials.
Password spraying – accounts were bombarded with common and weak password attempts (“123456”, “Password!”, seasonal or company-name variations), exploiting the statistical likelihood that at least a subset of admins used inadequate password hygiene.
Bot-driven login attempts with IP rotation – to evade lockout thresholds, adversaries deployed distributed bots that changed IP addresses constantly, mimicking legitimate traffic while maintaining a high rate of login attempts.
This blend of volume, automation, and credential reuse is a reminder that brute force—though primitive compared to APT zero-days—remains a lethal tactic when aimed at cloud authentication systems.
Phase 2: Breaching the Cloud Backups
With accounts cracked, attackers moved into SonicWall’s cloud backup storage. What they found were firewall preference files containing:
Encrypted passwords – safe from immediate decryption, but still potential targets for offline cracking attempts.
VPN keys and tokens – critical to establishing secure tunnels, now exposed for potential misuse.
Management settings – including configurations that govern remote management features (HTTP/HTTPS/SSH access), VPN parameters, and policies.
Even without plaintext passwords, these files are golden blueprints of how customer firewalls were structured. Attackers could study these preferences to engineer privilege escalation, disable security features, or introduce misconfigurations that make networks easier to breach. While SonicWall stressed that no ransomware hit their systems and no leaks have been confirmed publicly, the mere possession of these architectural details grants adversaries a reconnaissance advantage.
Phase 3: Collateral Risk to Victims
Fewer than 5% of SonicWall’s global customers were affected, yet the impact cuts deep. Those files belonged to administrators, IT security teams, and organizations that trusted SonicWall for perimeter defense. For these victims, the exposure represents:
Operational risk: attackers can analyze backup data to anticipate firewall behavior and plan targeted intrusions.
Credential exposure: even though encrypted, passwords may eventually be cracked offline, giving attackers authentic keys to systems.
Configuration intelligence: knowing which ports, VPN tunnels, or management services are enabled is invaluable reconnaissance.
Even organizations not directly impacted should take heed. Brute-force campaigns are not precision strikes; they are indiscriminate barrages that can just as easily pivot to other accounts, other vendors, or similar cloud services. The incident thus highlights the shared exposure of all organizations dependent on cloud-based firewall backups.
Phase 4: Reinforcing the Wall
SonicWall’s response was swift but telling. Customers were urged to immediately rotate all passwords, TOTP codes, and VPN keys, and to load only sanitized preference files provided by SonicWall. These updated files were randomized to eliminate compromised elements: new user passwords, new VPN keys, and reset bindings for MFA tokens.
Beyond SonicWall’s official steps, defenders must harden their posture:
Disable external management services (WAN/HTTP/HTTPS/SSH) unless absolutely necessary, cutting off one of the easiest attack surfaces.
Audit logs and configuration changes for anomalies, ensuring attackers haven’t already altered settings in ways that mask follow-on attacks.
Patch appliances and enforce MFA universally, with the strongest possible implementation to resist brute-force campaigns.
Treat recovery codes as privileged secrets, not casual fallbacks—because once stolen, they provide attackers with MFA bypasses.
The message is clear: resilience is not just about responding to compromise but building environments that are less brittle under brute force and reconnaissance-heavy campaigns.
Conclusion: Torpedoes Against the Defenders’ Walls
The SonicWall breach was not catastrophic in numbers, but it struck at the heart of trust. The irony is stark: a vendor that exists to reinforce organizational perimeters had its own backup walls torpedoed by one of the oldest tricks in the hacker’s arsenal—brute force.
For adversaries, the exposed files are not an immediate weapon but a strategic map, providing insights that could be used in future campaigns. For defenders, it is a wake-up call that supply chain resilience must extend to cloud backup practices, credential hygiene, and brute-force defense.
As ransomware groups like Akira continue exploiting SonicWall vulnerabilities, this incident highlights the convergence of cloud exposure, brute-force persistence, and supply chain fragility. The wall has not fallen, but the cracks are visible, and patching them requires urgency, layered defense, and a culture of treating even “backups” as attack surfaces.
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