A Structured Approach to Security Assessment
A network security audit is a systematic evaluation of an organization network infrastructure, policies, and controls. Unlike a penetration test that focuses on finding exploitable vulnerabilities, an audit provides a comprehensive assessment against a defined standard. Organizations should conduct external audits quarterly and full internal assessments annually.
The Seven-Step Audit Methodology
- Step 1 – Asset Discovery: You cannot secure what you do not know exists. Use network scanning tools (Nmap, Masscan) to discover all devices on the network. Supplement with SNMP queries, ARP table analysis from core switches, and DHCP lease inspection. The output is a complete inventory: every switch, router, firewall, server, printer, IP camera, and IoT device. Compare against existing CMDB records—the gaps are your first finding.
- Step 2 – Vulnerability Scanning: Deploy authenticated vulnerability scanners (Tenable Nessus, Qualys, OpenVAS) against all discovered assets. Authenticated scans provide deeper visibility by logging into systems and checking patch levels, configuration settings, and installed software. Prioritize findings using CVSS (Common Vulnerability Scoring System) scores, with critical (9.0+) and high (7.0-8.9) vulnerabilities requiring immediate remediation.
- Step 3 – Configuration Review: Compare device configurations against industry-standard benchmarks. The Center for Internet Security (CIS) publishes hardened configuration benchmarks for major platforms: Cisco IOS, Juniper Junos, Palo Alto PAN-OS, Fortinet FortiOS, and many others. Automate compliance checking with tools like Nipper, SolarWinds Network Configuration Manager, or custom scripts that parse running configs.
- Step 4 – Firewall Rule Analysis: Review every firewall rule for shadowing (a higher-priority rule that makes a lower-priority rule unreachable), overly permissive rules (any-any rules), unused rules, and rules without logging. Tools like FireMon, Tufin, and AlgoSec automate this analysis. Ensure the rule base follows a clean-up methodology with regular review cycles.
- Step 5 – Wireless Audit: Survey the physical environment for rogue access points using tools like Airodump-ng, Kismet, or commercial solutions like Ekahau. Verify that all authorized APs use WPA3-Enterprise where possible, with 802.1X authentication against RADIUS. Confirm that guest networks are properly isolated and that wireless intrusion prevention systems (WIPS) are active.
- Step 6 – Penetration Testing: Validate findings by attempting actual exploitation, but only in a controlled manner with appropriate authorization. Tools like Metasploit, Burp Suite, and custom scripts can test whether vulnerabilities identified in scanning are actually exploitable. Manual testing by experienced professionals remains essential—automated tools miss business logic flaws and complex attack chains.
- Step 7 – Reporting: Produce a prioritized report with executive summary, detailed technical findings, risk ratings, and clear remediation steps. Each finding should include CVSS score, affected assets, business impact, and effort required to remediate. Track remediation through to closure.
