SonicWall Security Breaches: What Really Happened With Legacy Passwords, Migrated Devices, and Ransomware Attacks?

If you’re a business running SonicWall firewalls, the last few weeks have likely been a roller coaster. Headlines warned of “zero-day SonicWall hacks” and a surge of Akira ransomware attacks, leaving IT teams scrambling for answers. Was there a hidden vulnerability lurking in your devices—or was something else at play?

Let’s get to the heart of the story. In this deep dive, I’ll break down what really happened, why fully-patched devices were still compromised, and, most importantly, what you can do to protect your organization—today and for the future. Whether you’re a cybersecurity pro or just responsible for keeping your company’s network safe, this article will give you clarity, confidence, and practical steps you can put into action.

Understanding the SonicWall Attack Surge: Fact vs. Fiction

First, let’s separate the facts from the fear. In late July, several cybersecurity researchers noticed a spike in Akira ransomware attacks targeting SonicWall customers. Some of these victims reported breaches even though their SonicWall devices were fully up-to-date and protected with Multi-Factor Authentication (MFA).

Cue the headlines: Was SonicWall facing a zero-day vulnerability?

The Zero-Day Rumor—And SonicWall’s Response

Zero-day vulnerabilities are every security team’s nightmare: previously unknown bugs that attackers can exploit before patches exist. But SonicWall quickly addressed the rumors. According to their updated advisory, there was no evidence of a new, unpatched vulnerability. Instead, most successful attacks could be traced back to legacy password use and migration oversights—especially involving the previously-publicized CVE-2024-40766.

Here’s why that matters: blaming mysterious bugs can sometimes distract from more common, preventable security gaps. Let’s unpack what really happened.

How Ransomware Actors Compromised SonicWall: The Human Factor

We all love to believe our technology is bulletproof with the latest patches. But attackers know that people—not software—are often the weakest link.

Passwords: The Lingering Legacy

Many organizations recently upgraded from SonicWall Gen 6 firewalls to the newer, more secure Gen 7 models. However, there was a catch: during migration, some IT admins imported old user account configurations—including passwords—without resetting them.

SonicWall’s original advisory had recommended resetting all local user account passwords as a critical step. Unfortunately, if this was missed, those old credentials (potentially weak or previously exposed) remained in use.

Why is this a problem?

Old passwords may have already been leaked in previous breaches (see: Have I Been Pwned)
Attackers can use brute-force methods to guess weak passwords, especially if additional protections aren’t enabled.
Even MFA can be circumvented if attackers have valid credentials and exploit flaws in implementation or user behavior.

The Role of Brute Force and MFA Bypass

Some SonicWall customers reported compromises even with Time-Based One-Time Password (TOTP) MFA enabled. How is that possible?

Brute-forcing Passwords: Attackers used automated tools to try countless password combinations until they succeeded.
MFA Fatigue: Some ransomware actors use tactics to overwhelm users with MFA requests, hoping a fatigued user will eventually approve.
Configuration Weaknesses: If MFA or anti-brute-force protections weren’t fully enabled, attackers had an easier path.

Key Point: Fully-patched firewalls aren’t invincible if the underlying user accounts are vulnerable.

CVE-2024-40766: Not a Zero-Day, But Still Dangerous

You may have seen references to CVE-2024-40766 in SonicWall’s advisory. This isn’t a new threat, but it’s still relevant.

What Is CVE-2024-40766?

It’s a previously-disclosed vulnerability affecting SonicWall’s SSLVPN (Virtual Private Network) service.
Attackers could exploit weak authentication measures to gain access, especially if strong passwords and up-to-date protections weren’t in place.
Official NVD Entry for CVE-2024-40766

Why Did It Matter During This Attack Surge?

Even though SonicWall had fixed the bug and provided clear guidance, failure to follow post-migration security best practices left doors open. For attackers, this was an opportunity—especially if organizations hadn’t:

Updated to the latest SonicOS version (7.3 or later)
Reset all migrated user passwords
Configured advanced security features (botnet protection, geo-IP filtering, etc.)

Lessons in Security Hygiene: Configuration Matters

If there’s a single lesson from this incident, it’s that security is not just about patches—it’s about processes. Even the best software can’t save you from weak passwords or overlooked steps.

Let me explain with an analogy: Upgrading your firewall without resetting passwords is like getting a new front door but reusing the old, lost spare keys.

Best Practices for SonicWall and Beyond

SonicWall’s updated statement and best-practice checklist are relevant to anyone managing network security. Here’s what you should do—immediately:

1. Update to SonicOS 7.3 (or the latest release)

This version includes built-in defenses against brute-force password and MFA attacks.
Download updates directly from SonicWall

2. Reset All Local User Account Passwords

Especially for accounts migrated from Gen 6 to Gen 7 firewalls.
Enforce strong password policies—random, complex, and unique for every user.

3. Remove Unused or Inactive User Accounts

Attackers love forgotten accounts. Regularly audit and delete any that are not needed.

4. Enable Botnet Protection and Geo-IP Filtering

These features block connections from known malicious IPs and suspicious regions.

5. Enforce MFA Everywhere

Not just for VPN access, but also for administrative accounts and remote logins.
Educate users on MFA fatigue attacks and encourage vigilance.

6. Monitor and Log Suspicious Activity

Use built-in logging and partner with threat intelligence providers (like Arctic Wolf, Google Mandiant, Huntress, Field Effect) to stay ahead of emerging threats.

Key Takeaways From the SonicWall Incident

Let’s summarize what matters most for organizations using SonicWall—or any network security appliance.

It wasn’t a zero-day. The breaches were mostly due to human error and misconfiguration after migration.
Passwords are still a top target. Old or weak credentials, especially those recycled across accounts, are easy prey.
MFA helps—but isn’t bulletproof. Proper implementation and user awareness are vital.
Follow vendor advisories closely. They’re not just boilerplate—they’re your roadmap for staying secure.

Frequently Asked Questions (FAQ)

Why were fully patched SonicWall devices still compromised?

Even with the latest software, devices were vulnerable because old passwords weren’t reset during migrations from Gen 6 to Gen 7. Attackers could exploit these legacy credentials, especially if their security had been previously compromised.

Is MFA enough to stop ransomware attacks on SonicWall devices?

MFA (Multi-Factor Authentication) greatly improves security, but it’s not foolproof. Attackers use tactics like brute-force, credential stuffing, and MFA fatigue. Strong passwords, proper configuration, and user education are also essential.

What is SonicWall CVE-2024-40766 and should I be worried?

CVE-2024-40766 is a previously disclosed vulnerability affecting SSLVPN. If you’ve updated to the latest SonicOS and followed all advisories—including password resets—you are protected. See the full details here.

What are the best practices for migrating from SonicWall Gen 6 to Gen 7?

Reset all local user passwords after migration
Remove unused accounts
Update to the latest SonicOS version (7.3+)
Enable advanced security features (botnet/geo-IP filtering)
Enforce strong password and MFA policies

Should I be worried if I haven’t migrated my SonicWall devices yet?

If you’re still on Gen 6, plan your migration carefully. Follow all SonicWall advisories to the letter—especially regarding password resets and configuration audits. Being proactive now will save you headaches later.

Where can I find the latest SonicWall advisories and updates?

Always refer to the official SonicWall Security Center for the latest news, advisories, and software downloads.

Conclusion: Security Is a Journey, Not a Destination

The recent SonicWall attacks are a sobering reminder: even the best tools still depend on how well we use them. There’s no shortcut around strong passwords, vigilant configuration, and ongoing education.

If you’re a SonicWall customer, take action today:

Update to SonicOS 7.3+
Reset all SSLVPN user passwords (especially post-migration)
Review your configuration and clean up unused accounts
Enable all available protection features

And remember, security isn’t just for headline-grabbing zero-days—it’s about daily discipline and smart, informed choices.

Stay safe, stay curious, and keep learning.
If you found this guide helpful, consider subscribing or sharing it with your team—because cybersecurity is stronger when we all know the facts.

Further Reading:

Thanks for reading—and here’s to a more secure, password-savvy tomorrow!

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SonicWall Security Breaches: What Really Happened With Legacy Passwords, Migrated Devices, and Ransomware Attacks?

Understanding the SonicWall Attack Surge: Fact vs. Fiction

The Zero-Day Rumor—And SonicWall’s Response