Firewalls are the first line of defense in today’s enterprise networks—but are yours configured to actually protect you?
A Firewall Security Audit is the most effective way to uncover misconfigurations, outdated rules, or missing patches that leave your organization vulnerable to threats. Whether you’re preparing for a compliance audit or simply tightening your defenses, this guide will walk you through how to perform a firewall security audit step by step.
What Is a Firewall Security Audit?
A firewall security audit is a comprehensive evaluation of a firewall’s configuration, ruleset, firmware, and operational integrity. Its purpose is to ensure the firewall aligns with your business’s security policies, industry compliance standards, and evolving threat landscapes.
At Securis360, our experts regularly conduct firewall audits to help businesses:
- Uncover misconfigured or overly permissive rules
- Ensure proper segmentation and zone isolation
- Identify unused or legacy firewall rules
- Confirm firewall firmware is up to date
- Meet compliance standards like SOC 2, ISO 27001, HIPAA, and PCI DSS
Why Is a Firewall Security Audit Important?
Firewalls are not “set-and-forget” tools. Over time, they can accumulate excessive rules, misconfigurations, or unpatched vulnerabilities. Without proper review, these gaps become easy entry points for attackers.
Here’s why regular firewall audits matter:
- Prevent Breaches: Catch risky configurations before attackers do.
- Ensure Compliance: Stay aligned with data security laws and frameworks.
- Optimize Performance: Remove redundant or overlapping rules to reduce latency.
- Improve Visibility: Gain better understanding of your traffic and access points.
- Align with Changes: Reflect network, team, or infrastructure changes in firewall rules.
How to Conduct a Firewall Security Audit in 7 Steps
Let’s break down how to perform an effective audit.
Step 1: Define Scope and Objectives
Start by clearly defining what you’re auditing and why. Are you:
- Reviewing a specific firewall or all across your environments?
- Checking compliance with SOC 2 or HIPAA?
- Evaluating your firewall post-merger or migration?
Example Objective: “Ensure that all outbound traffic from the finance network is restricted to approved IP ranges and applications.”
Step 2: Gather Required Information
Collect documentation, configurations, and logs including:
- Current firewall rulebase
- Network topology diagrams
- Firewall firmware versions
- Change management logs
- Previous audit reports (if any)
You’ll also need access to firewall management consoles and logging systems.
Step 3: Validate Firmware and Software Security
Security flaws in firewall firmware are a known attack vector.
Checklist:
- Are patches and updates applied?
- Are default credentials still enabled?
- Is secure management access (e.g., SSH over TLS) enforced?
- Are interfaces segmented by trust levels?
At Securis360, we recommend a quarterly check on firmware and software integrity.
Step 4: Review Change Management Processes
Firewall rules should only change via documented change requests.
Audit whether:
- All rule changes are logged with timestamps and reasons
- There’s a formal approval and rollback process
- Unauthorized rule modifications are flagged
This step is crucial for maintaining accountability and audit trails.
Step 5: Check for Regulatory Compliance
Depending on your industry, you may need to comply with:
- SOC 2 (for SaaS and service providers)
- HIPAA (for healthcare)
- PCI DSS (for finance and e-commerce)
- ISO 27001 (global standard for ISMS)
Ensure your firewall enforces:
- Data encryption
- Role-based access
- Zone isolation
- Monitoring and alerting policies
Securis360’s compliance-aligned templates streamline this process.
Step 6: Audit the Firewall Rules
This is the core of the audit.
Things to look for:
- Overly permissive rules (e.g., allow ANY source/destination)
- Redundant or shadowed rules
- Legacy rules with no current purpose
- Unnecessary inbound rules from the internet
- Rules that allow insecure protocols (e.g., Telnet, FTP)
Also validate:
- Logging is enabled on deny/allow rules
- NAT rules and ACLs are correctly implemented
- Proper use of zones (DMZ, Internal, WAN)
Use tools like Nmap, Wireshark, or Securis360’s firewall analyzer to validate rules in action.
Step 7: Resolve Identified Issues
Every finding should be documented and resolved via formal change control.
Remediation tips:
- Replace ANY rules with specific IPs or ports
- Decommission stale firewall rules
- Patch outdated firmware/software
- Enable alerting on suspicious activity
- Remove access for former employees or unused services
Follow up with post-remediation testing to ensure fixes are effective and haven’t introduced new vulnerabilities.
Firewall Security Audit Best Practices
Here are pro tips from the Securis360 audit team:
🔁 Audit Frequently
Perform firewall audits quarterly or after major infrastructure changes.
🗂️ Keep Documentation
Record findings, rule justifications, and change approvals for accountability and future audits.
⚙️ Leverage Automation
Use tools like Securis360 Firewall Audit Toolkit to detect unused rules, log gaps, and compliance misalignments faster.
📉 Review Logs Periodically
Look for anomalies in firewall logs that may indicate silent misconfigurations.
🧪 Test, Test, Test
Perform simulations (like port scans or segmentation tests) to verify rule effectiveness.
Tools Commonly Used in Firewall Audits
- Nmap – for network discovery
- Wireshark – for packet inspection
- Securis360 Rule Analyzer – for rule optimization and compliance checking
- Syslog Servers or SIEM Tools – for log aggregation and analysis
- Vulnerability Scanners – to test if firewall configurations are holding
Conclusion: Don’t Just Trust Your Firewall — Audit It
Your firewall might be active—but is it actually defending your organization?
A Firewall Security Audit gives you the clarity, control, and confidence needed to know your network perimeter is secure. Whether you’re preparing for an audit, optimizing performance, or just tightening internal controls, auditing your firewall is a non-negotiable.
At Securis360, our firewall audit experts combine industry frameworks like MITRE ATT&CK and Zero Trust Architecture to harden your defenses against evolving threats.
📩 Need a professional firewall audit or SOC 2 alignment?
Get in touch with Securis360’s team of certified cybersecurity experts.