Internal vs. external vulnerability scanning: Meaning and differences

It’s not enough to react only when a security issue arises — you have to be proactive and conduct internal and external vulnerability scans if you want to protect your company from security breaches. By knowing where a threat actor may strike, you can patch the weakness before they become serious problems. Learn about internal vs. external scanning and how your company can benefit from both.

What is vulnerability scanning?

Vulnerability scanning is a key security practice that helps businesses find weaknesses in their systems before attackers can exploit them. It’s an automated process that checks for risks in software, networks, and devices. Depending on what’s being scanned, it can be either internal or external:

• Internal vulnerability scanning checks for security weaknesses inside your company’s network, like outdated software, misconfigurations, or weak passwords. These scans are a crucial part of a broader vulnerability assessment strategy, ensuring that hidden risks inside your infrastructure don’t go unnoticed.
• External vulnerability scanning locates security gaps in the internet-facing parts of your network, such as open ports, outdated software, misconfigurations, and unprotected APIs, to prevent unauthorized access.

Automated internal and external vulnerability scans save your IT team some precious time and help them with [vulnerability management]. The findings from these scans inform your IT crew about what they need to patch for your company to withstand cyberattacks and security breaches. For example, an internal scan might detect misconfigurations that could allow an attacker to drop infostealer malware onto a company workstation to silently extract passwords and sensitive data.

But these scans aren’t just for the company — businesses must conduct them to comply with industry standards and regulations, such as HIPAA (the Health Insurance Portability and Accountability Act) in the US, the GDPR (General Data Protection Regulation) in the EU, and the globally recognized PCI DSS (Payment Card Industry Data Security Standard). These regulations obligate businesses to safeguard customer and employee information from cyber threats, data breaches, and misuse.

Let’s take a closer look at both types of vulnerability scanning, how they differ, and why they’re a must-have for any solid cybersecurity plan.

Internal vs. external vulnerability scanning

Internal vulnerability scanning and external vulnerability scanning have only one thing in common — they both locate vulnerabilities. But they’re different in all other aspects, including scope, purpose, and the attack surface.

Internal vulnerability scanning: How does it work?

Internal scans operate within your network’s boundaries. The process typically starts with mapping out internal devices — workstations, servers, and applications — followed by scanning them for weak passwords, outdated software, and misconfigurations. The scan results help IT teams pinpoint vulnerabilities that insiders or malicious software could exploit, so they can patch security gaps before they become a real problem.

For example, an internal scan might identify outdated software versions or weak passwords that make it easier for hackers to break in. Think of an internal scan as checking the locks and alarms inside your house to make sure that, even if someone gets in, they can’t easily get to where you keep your most valuable belongings.

Benefits of internal vulnerability scanning

Regular internal scans help your IT crew fend off cyber threats and keep systems running smoothly. Let’s take a closer look at how your business can benefit from these scans.

• Catch security gaps before attackers do. Fixing them early reduces the risk of a breach.
• Protect against insider threats. Employees, contractors, and people who have access to compromised accounts won’t be able to misuse vulnerabilities if you fix them in time.
• Keep systems compliant. Regular internal scans help your business to stay compliant with regulations like HIPAA, the GDPR, and the PCI DSS.
• Prevent malware from spreading. If an attacker gets in, they can exploit weak spots to spread malware across your network—but not if regular scanning catches those risks first.
• Improve overall system performance. By identifying outdated or vulnerable software, you can keep your systems running smoothly.
• Reduce potential downtime. Security incidents can shut down operations, but not spotting and fixing internal vulnerabilities early helps you avoid costly disruptions.

When should you perform internal vulnerability scanning?

Your company should regularly scan for internal vulnerabilities, ideally weekly or monthly. You should also conduct them after system updates, software patches, and configuration changes to make sure you didn’t leave anything exposed.

Whenever you add new devices like servers or workstations, you should also scan them for weaknesses. If a security incident occurs, an immediate scan helps identify and fix exploited vulnerabilities.

Lastly, do an internal scan before compliance audits to make sure everything is up to snuff.

Internal vulnerability scanning examples

One common risk that internal scans uncover is outdated software. For example, they might detect that many employees are still using an old version of an office app, leaving the system vulnerable to exploits. With this information, the IT team can encourage employees to update the app to a secure version.

The same goes for passwords. If a scan reveals that multiple employees are still using weak passwords like “123456” or “Company2024,” you can remind them to update their credentials, implement a company-wide password manager, or even run a quick cybersecurity refresh for the team.

External vulnerability scanning: How does it work?

External vulnerability scanning focuses on your organization’s outward-facing assets — it checks public IP addresses, websites, and network perimeters for vulnerabilities. The process typically starts by identifying all externally accessible systems, then scanning them for weaknesses like open ports, outdated software, or misconfigured firewalls.

The results highlight potential entry points that attackers could exploit and allow the IT team to take action, whether that’s patching vulnerabilities, reconfiguring security settings, or tightening access controls.

Think of an external scan as checking your property’s fences, doors, and windows to make sure they’re locked and secure — because if someone is looking for a way in, you don’t want to make it easy for them.

Benefits of external vulnerability scanning

If internal scans identify what could go wrong on the inside, external scans reveal the weak spots attackers could exploit to break in. Let’s look at how your company will benefit from these scans in more detail:

• Identifies weak points before attackers do. External scans uncover open ports, outdated software, and misconfigured firewalls that could be easy entry points for hackers. Fixing them early strengthens your defenses.
• Reduces the risk of data breaches. By spotting vulnerabilities in public-facing systems, external scans help prevent unauthorized access to sensitive company and customer data. When combined with data breach monitoring, these scans provide businesses with a proactive approach to cybersecurity.
• Keeps websites and services secure. If your website or cloud systems have security gaps, external scans will flag them so your IT crew can patch them right away.
• Helps meet compliance requirements. Regular scans make compliance with the PCI DSS or GDPR easier and help you avoid penalties.
• Supports a proactive security strategy. Instead of waiting for a cyberattack, external scans give you a chance to fix security flaws before they become real problems.
• Improves firewall and perimeter security. Scans check if firewalls, intrusion prevention systems, and other perimeter defenses are working as they should. If anything is exposed, you’ll know right away.

When should you perform external vulnerability scanning?

Your company should regularly scan for external vulnerabilities, ideally monthly or quarterly, to stay ahead of security risks. You should also run a scan after firewall updates, software patches, or changes to public-facing systems to ensure nothing was left exposed. Whenever you launch a new website, cloud service, or public-facing application, scan it for security gaps before it goes live.

If there’s a security breach or a suspicious attempt to access your systems, running an immediate scan can help identify weak spots and prevent further attacks. And before a compliance audit, an external scan helps confirm that your defenses are up to standard.

External vulnerability scanning examples

An external scan can uncover firewall misconfigurations that expose sensitive company data. For example, it might reveal that certain internal files are unintentionally accessible from the internet due to overly permissive firewall rules. This kind of oversight could allow unauthorized users to view confidential reports, customer records, or financial data. By catching the issue early, the IT team can adjust firewall settings to restrict access and prevent potential data leaks.

Another common example of what external scans detect is outdated encryption on login pages. A scan might flag your company’s web portal for still using an older encryption protocol that is no longer secure. Attackers could exploit this weakness to intercept login credentials, putting employee and customer accounts at risk. Once you’re aware of this weakness, you can upgrade to a more secure encryption standard.

Credentialed vs. uncredentialed vulnerability scanning

Also known as authenticated and unauthenticated scans, credentialed and uncredentialed vulnerability scans serve different purposes in cybersecurity testing.

A credentialed scan uses login credentials to access internal systems like an authorized user and looks more deeply at vulnerabilities that wouldn’t be visible from the outside. This type of scan can flag issues such as outdated software on employee workstations, weak encryption in internal applications, or misconfigured security settings on servers — all of which an attacker could exploit if they gained access.

An uncredentialed scan, on the other hand, checks for vulnerabilities from an outsider’s perspective. It simulates how an attacker would scan public-facing systems without logging in. For example, if an uncredentialed scan detects open ports or an exposed admin panel, it means an attacker could find and target them too.

Since both scans reveal different types of risks, companies use a combination of credentialed and uncredentialed scanning to get a complete picture of their security posture.

You may wonder, what’s the difference between internal and external scans versus credentialed and uncredentialed scans? Credentialed and uncredentialed scans focus on how a scan is conducted — whether it has login access or not. In contrast, internal and external scans focus on where the scan takes place — inside the network (internal) or from an outsider’s perspective (external).

Why are external and internal vulnerability scans crucial for your business?

Cyber threats don’t just come from one direction. Attackers can exploit public-facing weaknesses to break in, or they can take advantage of internal security gaps to move across your network. That’s why your business needs both external and internal vulnerability scans. These scans work together to catch risks before they become full-blown security incidents.

External scans protect everything the outside world can see — your website, cloud services, and any system accessible from the internet. If a scan detects an exposed entry point, you can lock it down before an attacker gets in, shutting the door on unauthorized access. That’s exactly what NordStellar’s external vulnerability scanner does — it helps your security team to identify and take control of risks across your internet-facing infrastructure.

Internal scans focus on what’s happening inside your network — workstations, servers, and applications employees use daily. Even if your external defenses are secure, a weak spot inside can give an attacker free rein once they get in. Without internal scanning, you might not realize the risk exists until it’s too late and sensitive data has already been compromised.

Beyond preventing attacks, these scans save time and money by reducing emergency fixes, help businesses meet compliance standards like PCI DSS and GDPR, and keep systems running smoothly by identifying outdated software before it causes performance issues.

Skipping vulnerability scans is like never checking the locks on your house — you might not see the risk immediately, but the moment someone tries to break in, you’ll wish you had. Regular external and internal scans give your business the chance to spot and fix vulnerabilities early. They also strengthen overall security and prevent costly disruptions.

Other ways to protect your business from cyber threats

Regular vulnerability scans are essential, but they’re just one piece of a solid cybersecurity strategy. To strengthen your defenses, make sure your team follows basic security best practices — use strong, unique passwords, enable multi-factor authentication, and keep all software up to date. Data breach monitoring can also help by alerting you if sensitive company information appears on the dark web.

Beyond that, train employees to recognize phishing attempts and suspicious activity, limit access to sensitive systems, and use endpoint protection tools to block malware before it spreads. But staying secure isn’t just about reacting to threats — it’s about seeing them coming.

That’s where a threat exposure management platform comes in. A platform like NordStellar offers dark web monitoring to help you identify compromised employee and consumer credentials so you can secure your accounts before it’s too late. With NordStellar, you can identify and address cyber threats aimed at your company before they escalate.

FAQ

What is the main difference between internal and external vulnerability scans?

The main difference between internal and external vulnerability scans is the attack surface. Internal scans check for security gaps inside your network, focusing on risks that could be exploited by someone with access, like an employee or a hacker who got in. External scans look for weaknesses in internet-facing systems, like websites or firewalls, that attackers could target from the outside.

What are the similarities between internal and external vulnerability scans?

Both internal and external vulnerability scans identify security weaknesses in a network and help prevent cyberattacks. They use similar scanning techniques, check for outdated software, misconfigurations, and known vulnerabilities, and provide reports with risk assessments and recommendations. Their goal is the same — to strengthen security before attackers can exploit weaknesses.

Do you need to use both internal and external vulnerability scanning?

Yes, using both internal and external vulnerability scanning is important for strong security. Internal scans help identify risks within the network, while external scans focus on threats from outside. Together, they give a complete view of your company’s vulnerabilities and help prevent potential attacks from all angles.