When Firewalls Do Not Work: The Threat to Network Security

If Down firewall = hacker’s opportunity — in the best of ways!

I’ve been in this industry since before firewalls were within every business network. My initial exposure to network security threats? It taught me why perimeter security matters—real fast: The Slammer worm. The reality, however, is that even today firewalls go dark way too much for most IT teams to admit. And when that happens? Attackers notice.

I’ve just returned from DEFCON (still reeling from that hardware hacking village—crazy!), and I can tell you this: your firewall is one of the few things protecting your business from a full-fledged breach. When it goes down? You’re rolling the dice on your network security.

Let’s explore the reasons why firewall outages pose such a significant risk and what can be done about it.

Role of Firewalls in Security

Your firewall is not a box on a rack—it represents your first line of defense.

Here’s what it does:

• Prevents unauthorized access to your network.
• Filters incoming and outgoing traffic (so malware doesn’t slip through undetected).
• Enforce security policies — who can see what
• Prevents DDoS attacks, port scanning and brute force.

It’s similar to how you would like to keep the front door of your house — would you leave it wide-open at night? No? So, why let your firewall go down un watched.

Increased Cyberattack Risks

When that firewall falls, even temporarily, the extent of your attack surface explodes.

I’ve watched this occur firsthand; one of the banks we were partnered with had a 20-minute firewall failure. In that tiny window, we saw:

• A sudden spike in port scans — automated bots probing for weaknesses within seconds.
• Multiple login attempts from malicious locations.
• Attack attempts on unprotected services.

The scary part? Even worse: The vast majority of IT teams don’t even know when these scans take place. Hackers are opportunists. When a firewall goes dark, attackers with continuous scanning tools get alerted—and that’s when they pounce.

The reality is that your business may not face direct attack the moment your firewall drops. But downtime raises the threat of:

• Malware infections due to protections being temporarily disabled.
• Information stealing if a backdoor is pre-existent.
• Privilege escalation attacks, where attackers get more access than they are meant to have.

And let’s keep it 100 — firewall rules and ACLs have limits. Consider your network exposed if your firewall is unavailable.

Common Downtime Exploits

What does this mean in practical terms when your firewall is offline? Well, hackers are not waiting patiently in the wings. They have an opening and they begin hammering.

Common real-world attacks I have encountered are:

• Port Scanning Reconnaissance
  • Attackers search for open services.
  • They will quickly attempt brute-force logins if RDP (3389) or SSH (22) is open.
• Exposed Services Exploitation
• With no firewall to block traffic, once-vulnerable systems, now unpatched, become targets of choice.
• SMB bugs (WannaCry ring a bell?)
• Man-in-the-Middle Attacks
• Attackers may be able to intercept credentials if internal traffic is not encrypted.
• DDoS to Distract IT Teams
• As your squad scrambles, attackers use secondary exploits to get inside.

I remember there was a case in 2005 when an ISP I worked with had a firewall failure. Within 10 minutes? They had no idea they were dealing with malicious router reconfigurations — working around their security protocols altogether.

Security Details of PJ Networks

At PJ Networks we cannot afford firewall downtime. We have 24/7 monitoring so if a firewall even blinks, we catch it.

Here’s how we work to mitigate risk:

• Proactive Monitoring
  • Automated alerts — so we know immediately when there’s an outage.
  • Ongoing threat intelligence feeds observing attack patterns.
• Zero Trust Architectures
  • Just finished working with three banks on zero-trust upgrades, firewall or no firewall — internal access is all locked-down.
  • Microsegmentation—attackers are trapped if they get in.
• Excessive Firewall Systems
  • Failover appliances so a single firewall failure doesn’t expose clients.
  • Firewall as a service backup (as a firewall on-prem isn’t enough).
• Incident Response Playbooks
  • When an outage occurs, we don’t panic—we deliver.
  • Provisions are in place to maintain authorized users during downtimes.

Look, IT happens. Firewalls fail, updates bring down devices, and vendors screw up. But how a plan makes all the difference. That’s the difference between a minor nuisance and a major security incident.

Conclusion

At this point, firewalls are not a “nice to have” — they are “must-have” critical infrastructure. Your security risks grow exponentially when they go down, even for a few minutes.

I’ve been in this industry since the early ’90s, and I’ve seen all sort of security gaffs. One truth has never altered: Attackers exploit gaps. A down firewall? That’s a huge, blinking hole in your security perimeter.

So—watch your firewalls, maintain redundancies, and treat downtime as if it matters. Because threats are not going down. They’re evolving.

And believe me, if you’re not watching your firewall, somebody is.