How to Conduct A Network Security Audit

published
July 10, 2024
TABLE OF CONTENTS

Network securing audits review your corporate network defenses for vulnerabilities that may be exploited by cybercriminals and other threat actors. They are a thorough health checkup for your IT infrastructure.

Conducting network security audits is an ongoing process. It requires diligence and a proactive mindset. By frequently auditing your network for vulnerabilities, you can stay ahead of potential threats and keep your corporate data safe.

Internal vs. external network security audits

Internal audits are conducted by your IT team or an internal audit team. They're like a self-check. You know your systems, your setups, and where the skeletons are buried. 

You know those corner-case configurations that haven't been updated in years or the little shortcuts taken to get around a tricky setup. You have the advantage of familiarity. But that same advantage can sometimes be a double-edged sword. Your team might overlook issues due to bias or lack of fresh perspective.

External audits are on the opposite spectrum. These are performed by third-party vendors or consultants. Think of them as the fresh pair of eyes you sometimes need. 

External auditors bring in a wealth of experience from different industries and companies, which means they can spot weaknesses that your team might miss. They can also provide a broader range of solutions based on what they've seen work elsewhere. 

For instance, an external auditor might identify a vulnerability in your network segmentation that your team didn't even know existed because it's common knowledge outside your organization but not internally.

One key difference between internal and external network security audits is in the reporting. Internal audits might be more informal, depending on your company's policies. They might be more of a checklist run-through. 

External auditors, however, typically provide a detailed report complete with findings, risk assessments, and recommendations. This report can be crucial for compliance purposes or when presenting to stakeholders who need an unbiased perspective.

Cost is another consideration when choosing between the two options. Internal audits, by default, are cheaper since you're using existing resources. However, they can still be resource-intensive in terms of time and effort. 

External audits can be pricey, but they might provide value that's hard to quantify—like increased security posture and peace of mind. For example, after an external audit, a company might find and patch a critical vulnerability that could have led to a significant data breach, saving potentially millions in losses and reputational damage.

In terms of frequency, internal audits can be conducted more regularly, maybe even monthly or quarterly. They are more about maintaining ongoing vigilance. External audits, due to their cost and scope, are usually done annually or bi-annually. 

Each type of audit has its place, and ideally, a combination of both should be part of your network security strategy. Internal audits help maintain day-to-day security, while external audits offer a comprehensive periodic check-up to ensure nothing slips through the cracks.

Manual vs. automated network security audits

Both manual and automated security audits have their strengths and weaknesses, and often, the best approach is a mix of both.

Manual audits involve a human touch, which can be invaluable. You can dive deep into the intricacies of your network, spot nuanced issues, and apply your expertise where it matters most. 

For example, a manual audit might reveal subtle misconfigurations or outdated firewall rules that an automated tool might overlook. The human eye can catch context-specific vulnerabilities and adapt quickly to unexpected scenarios. However, manual auditing is time-consuming and prone to human error, especially in large, complex networks.

Conversely, automated network security audits leverage tools and software to scan your network efficiently and consistently. Automated tools can run scheduled scans, ensure no stone is left unturned, and provide standardized reports. 

For example, tools like Nessus or OpenVAS can quickly identify known vulnerabilities across thousands of devices. These tools are great for maintaining a baseline security posture, handling repetitive tasks, and freeing up your time for more detailed analysis. But they are only as good as their most recent update and might miss new or evolving threats that don't match their databases.

You must also consider how automated tools can sometimes generate false positives or miss context-specific issues that a human auditor would catch. For instance, an automated tool might flag a legitimate data transfer as suspicious simply because it doesn't fit known patterns. Here, human expertise is essential to differentiate between false alarms and genuine threats.

In practice, a hybrid approach often works best. You can use automated tools to handle the heavy lifting — scanning the network, identifying known vulnerabilities, and generating initial reports. Then, you follow up with manual audits to analyze the results, investigate flagged issues, and make context-aware decisions. This combination allows you to be both efficient and thorough, leveraging the strengths of both methods.

Combining these approaches ensures your corporate networks remain robust and secure. You get the best of both worlds: the efficiency and consistency of automation, paired with the insight and adaptability of human expertise.

Common vulnerabilities a network security audit must expose

Outdated software or systems

A network that runs on outdated technology is exposed to all manner of risks. For example, running an old version of Windows that no longer gets security updates can open the door to attackers.

Misconfigured network settings

Poorly configured networks can expose sensitive data or allow unauthorized access. For instance, if your firewall isn't properly configured, it might leave certain ports open, making it easier for an attacker to get in.

Unencrypted data flows

It’s crucial to assess how data flows within the network. Data should be encrypted, especially when it's moving from one place to another. If you find data being transmitted in plain text, it’s an immediate concern because anyone can read it.

Loose user access controls

Every user shouldn’t have admin rights. It's important to follow the principle of Least Privilege, meaning users get access only to the resources they need for their job. A scenario where every employee had admin access is like giving everyone the keys to the kingdom; it’s an unnecessary risk.

Weak passwords

Network security audits must expose weak password policies. Passwords like "123456" or "password" must not be used on an enterprise network. They are the equivalent of leaving your car keys in the ignition. 

Implementing multi-factor authentication (MFA) can significantly improve security by adding another layer of verification. So even if someone steals or correctly guesses a password, they can't get in without the second factor.

Undocumented incident response plan

Every company should have a documented and tested plan for what to do if there's a security breach. It’s surprising how many don’t. It’s like having a fire escape plan for your home; you hope you never need it, but you must have one.

Why conducting security audits is crucial for company networks

Boosts compliance

Undertaking regular network security audits is pivotal not just for identifying vulnerabilities, but also for ensuring compliance with industry regulations and standards. This means you are not only securing your network but also aligning with laws like GDPR, HIPAA, or PCI-DSS. 

GDPR mandates strict data protection measures. By auditing your network, you can pinpoint if your data encryption practices are up to scratch, or if sensitive information is being inadvertently exposed.

When you perform these audits, you are essentially holding up a mirror to your network's defenses. It's a proactive approach. Instead of waiting for a breach to occur, you identify and rectify issues beforehand. 

The PCI-DSS standard, for instance, requires organizations that handle credit card information to maintain a secure environment. Without regular audits, you might miss critical vulnerabilities like unpatched software or weak access controls that could lead to non-compliance and hefty fines.

Moreover, audits help you to stay updated with compliance requirements that are continually evolving. Cybersecurity threats are constantly changing, and so are the regulations. By regularly auditing, we ensure our security measures grow and adapt. 

HIPAA, a standard those in healthcare must comply with, has stringent rules about safeguarding patient data. An audit can reveal if your protocols for accessing and transmitting patient information are in line with these rules, or if we need to boost your security measures.

Audits also offer the chance to educate and train your staff. When issues are identified, it provides a teachable moment. You can explain the compliance requirements and the steps needed to meet them. 

If you discover that some employees are unaware of the proper procedures for handling sensitive data, you can provide targeted training to fill that knowledge gap, ensuring everyone is on the same page.

Therefore, consistent network security audits put you in a stronger position to meet and exceed compliance requirements. They help ensure that your network is not just secure but also compliant with the latest standards and regulations. This dual focus on security and compliance fortifies your defenses and underscores our commitment to safeguarding data.

Enhances overall security posture

Network security audits help identify vulnerabilities before they can be exploited. For example, discovering an open port that shouldn’t be accessible from the outside allows you to take immediate action to close it and prevent unauthorized access.

A network security audit also includes reviewing password policies. Weak passwords are often the easiest way for attackers to gain entry. During an audit, you can check if employees are following guidelines for strong passwords, like using a mix of letters, numbers, and special characters.

Another critical aspect of network audits is ensuring software is up-to-date. Outdated software can have known vulnerabilities that attackers exploit. During an audit, you scan for any outdated systems and schedule updates. Updating these immediately reduced the risk of a potential breach.

Security audits also verify that firewall rules are configured correctly. A misconfigured firewall rule can allow unrestricted access to internal databases. Intrusion detection systems must also properly log and alert you to any suspicious activities.

Audits are also an opportunity to review user access controls. Not everyone needs access to every part of the network. By reviewing user permissions, you can limit access to sensitive areas only to those who need it. For instance, former employees must not retain access to your systems.

Lastly, network security audits often reveal areas where staff training can be improved. Sometimes, simply educating employees about phishing attacks can prevent a potential breach. For instance, a mock phishing test can find that several employees clicked on the malicious link, which highlights the need for better staff training on recognizing phishing attempts.

How to conduct a network security audit

Phase 1: Information gathering

Gathering information is similar to preparing a battlefield map. You want to know every detail about the network, its components, and any possible entry points or vulnerabilities.

You start with the basics—IP addresses, domain names, and organizational structure. Document all external IP addresses assigned to the company. Also, gather details on all domain names registered under the company. This gives you a clear picture of your digital footprint.

Next, look at the infrastructure. This means identifying all network devices, such as routers, switches, and firewalls. For instance, you might discover that your company uses Cisco routers and Palo Alto firewalls. Knowing the make and model helps you understand the potential vulnerabilities associated with these devices.

You should then move on to the software. Make an inventory of all your operating systems and version details. If your servers run on Windows Server 2019 and their workstations use Windows 10, you should take note. Each version has its own set of known vulnerabilities and patches, which is essential information for your audit.

Another critical step is understanding the services running on the network. You may find that you have several ports open for web services (ports 80 and 443) and email (port 25). Each open port is a potential entry point for attackers and needs to be scrutinized.

You should also gather information on user accounts and their privileges. If you have a domain-wide admin account accessed by multiple users, this is a red flag. Examine the policies surrounding user privileges to ensure they align with security best practices.

Then, there's the human element. Conduct interviews with key personnel to understand the network's operational aspects and any known issues. If you have had recent issues with phishing attacks, that's something you need to prioritize.

Lastly, we check external sources for relevant information. This includes looking up past security incidents involving yours and similar companies. Public vulnerability databases like the CVE (Common Vulnerabilities and Exposures) list can provide insights into potential risks.

Information gathering is a mix of technical probing and detective work. Each bit of information helps you build a comprehensive picture of the network, preparing you for the next phases of the security audit.

Phase 2: Vulnerability assessment

Phase 2 is where you identify the weaknesses in your network. It’s where you poke around to see where the cracks are. Your goal here is to find those cracks before anyone else does.

You should start with automated tools. Tools like Nessus and OpenVAS can scan your network for known vulnerabilities. They’re pretty good at finding issues quickly. 

For example, Nessus might alert you to an open port that's been forgotten about. That’s a big deal because an open port can be an easy entry point for attackers.

Next up is manual testing. Automated tools are great, but they can't catch everything. That's where your skills come in. You manually review configurations and actively test for vulnerabilities. You may discover an outdated software version or a web server that hasn't been patched in months. That’s a potential risk, and you need to patch it immediately.

In this phase, you also look at misconfigurations. Misconfigured firewalls, for instance, can be gateways for intrusions. Maybe a firewall rule is too permissive. Instead of blocking specific IP addresses, it allows traffic from any source. That’s a serious gap we need to close.

You must also audit for unauthenticated scans. Sometimes vulnerabilities hide behind authentication barriers. Running scans with proper credentials can reveal issues that unauthenticated scans won't catch. For instance, an authenticated scan might uncover that user passwords are not adhering to your complexity requirements.

Finally, you must document everything. Every vulnerability, every misconfiguration, every outdated software. This documentation helps you track what needs fixing. It’s also a roadmap for Phase 3, where you start remediating these issues.

Phase 3: Risk assessment

The risk assessment phase identifies and evaluates the potential threats to your network. You need to understand what could go wrong and how it might impact your operations.

Start by listing all the critical assets within your network. This includes servers, databases, and even sensitive information. For example, your customer database is a goldmine that needs protecting. If someone unauthorized gets access to it, the damage could be extensive, both in terms of your reputation and regulatory penalties.

Next, consider the vulnerabilities. These are weaknesses that could be exploited. Maybe your firewall rules are outdated, or perhaps there's a known bug in the software you use, for example, an old version of a web server that has a security flaw. You must address these before they become a problem.

After the vulnerability assessment, you assess the threats. These are the actors or events that could exploit those vulnerabilities. Hackers, disgruntled employees, or even natural disasters like floods. For instance, a hacker group might target your network due to known vulnerabilities in your software, or an employee might misuse their access privileges.

You also need to evaluate the likelihood of these threats materializing. Is it a rare occurrence, or something that's highly probable? For example, if your office is in a flood-prone area and our servers are in the basement, the likelihood of water damage is pretty high. 

Finally, consider the impact of those risks. What would be the business consequence if one of these risks materializes? This involves considering both the immediate and long-term effects. If your customer database is breached, you could face immediate financial losses and long-term damage to your reputation.

By systematically going through these steps, you can prioritize which risks need urgent attention. Maybe the outdated firewall rules are an easy fix and can significantly reduce your vulnerability, or perhaps you need to invest in flood-proofing your server room.

Risk assessment isn't about eliminating all risks because that's impossible. It's about making informed decisions to minimize them as much as you can, ensuring your network remains secure and your business operations uninterrupted.

Phase 4: Testing and evaluation

This is where you put everything under the microscope to see if your network's defenses are up to the task. To start, you run a series of vulnerability scans. These scans help identify any weak spots in your network. 

Again, you can use tools like Nessus or OpenVAS for this. They comb through every corner, looking for outdated software, misconfigurations, or any other gaps that hackers could exploit. For instance, if there's an old version of Apache running on one of your servers, these tools will flag it right away.

Next, dive into penetration testing. This is where you simulate attacks on your network to see how well it stands up. You might use Metasploit to launch an attack. This could involve trying to break into a server or see if you can escalate your user privileges. 

The goal here is to find out if someone with bad intentions could get in and what damage they could do. It's like hiring a professional safecracker to test the bank vault.

Then, you look closely at your firewall rules and access controls. You review the configurations to ensure they match your security policies. 

Sometimes, you find overly permissive rules that could let unwanted traffic slip through. For example, a rule allowing all incoming traffic on port 22 (SSH) might be too broad. You should tighten these rules to only allow trusted IPs.

You also evaluate your incident response procedures. You carry out mock attacks, like a ransomware attack or a data breach, to see how your team reacts. This helps you understand if your procedures are effective and if your team knows what to do under pressure. A well-coordinated response can make all the difference in minimizing damage during a real incident.

User access reviews are another critical part of this phase. Audit user accounts and permissions to make sure everyone has the right level of access. Often, you find accounts that haven't been used in months or have more privileges than necessary.

Finally, check your logging and monitoring systems. Ensure they are capturing all the necessary data and that alerts are working correctly. Tools like Splunk or ELK stack come in handy here. Set up alerts for suspicious activities, such as multiple failed login attempts, which might indicate a brute-force attack.

Testing and evaluation should be about improving our defenses, not just finding problems. Every vulnerability you find and fix makes your network stronger and more resilient against threats.

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