Internal Vs External Vulnerability Scanning

Regrettably, you’re always at risk of developing vulnerabilities that hackers can exploit from both inside and outside your network infrastructure.

Therefore, we always recommend that our clients consider internal and external vulnerability scanning as a priority so that no weaknesses are left unchecked.

However, it’s a common misconception that you only need one or the other to keep your network, data, and customers safe.

In this guide, we’ll take you through what’s involved in both internal and external scanning, what the main differences are, and what to consider when choosing the right service for each.

What is Internal Vulnerability Scanning?

Internal vulnerability scanning is a security process that identifies weaknesses within your internal network that external scans and tests would otherwise miss. Ultimately, internal scanning spots vulnerabilities that hackers can exploit after they’ve broken through your perimeter defenses.

You can then use the data from internal scan reports to make adjustments to your security plan and to better fortify your network against bad actors.

Internal scans spot flaws within your IT infrastructure, such as weak internal password usage, lax hardware and software updates, weak endpoints and connected hardware, and insufficient maintenance schedules.

What’s more, we always remind our clients of the threat of internal cybercrime. As mentioned, it’s wise to tighten up your internal security in case a bad actor breaks in – but, as Cybersecurity Insiders’ research points out, almost half of organizations feel that internal threats are becoming more concerning:

“48% of organizations reported that insider attacks have become more frequent over the past 12 months. Additionally, 51% experienced six or more attacks in the past year, with the average cost of remediation exceeding $1 million for 29% of respondents.”

Cybersecurity Insiders

What is External Vulnerability Scanning?

External vulnerability scans analyze your security from an outside perspective, for example, finding weaknesses that hackers can exploit to gain access to your internal data. We typically recommend running external scans alongside penetration tests to gain insight into attackers’ points of view.

External vulnerability scans help you to find weaknesses that could allow malware, ransomware, DDoS (Distributed Denial of Service), and cross-site scripting attacks to wreak havoc.

Scanning externally can find weaknesses in web forms, password control, firewall setup, data encryption, and even personnel knowledge and training. After all, more than eight in ten employees are prone to fall for elaborate phishing attacks:

“Within the first 10 minutes of receiving a malicious email, 84% of employees took the bait by either replying with sensitive information or interacting with a spoofed link or attachment.”

Cybersecurity and Infrastructure Security Agency (CISA)

Like internal scanning, external scanning helps to lay cybersecurity weaknesses out flat. When working with our clients, we typically run both types of vulnerability scans as preliminary measures before running deeper penetration tests and then remediating problems.

Internal vs External Vulnerability Scanning: Key Differences

Let’s break down what you need to know about vulnerability scanning when comparing internal and external methodologies:

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Beyond internal vs. external vulnerability scans, it’s also worth considering credentialed and unauthenticated scans, too.

Credentialed scans take place when you have complete, authenticated access to a full network or system, and can therefore perform deeper analysis. Unauthenticated scans, meanwhile, don’t require authentication and therefore don’t scan as comprehensively as authenticated scans.

Both can be highly useful when tightening up your security posture. Credentialed scans allow you to see all your potential weaknesses clearly and help you to prioritize remediation.

Unauthenticated scans, meanwhile, are more efficient—and, while they don’t need administrative access or have as thorough a scope as credentialed scans, they are highly effective as surface-level, initial tests before proceeding with deeper analysis.

Benefits and Use Cases of Each Scan Type

Both internal and external vulnerability scans serve distinct roles in a well-rounded cybersecurity program. Understanding when and why to use each helps ensure full coverage against modern threats.

Internal vulnerability scanning is designed to uncover risks within your internal systems—areas that external scans can’t reach. These scans are especially helpful in maintaining strong access controls, detecting insider threats, and supporting compliance with frameworks like HIPAA and PCI DSS.

Key benefits:

• Identifies misconfigurations, weak credentials, and outdated software inside the network
• Strengthens endpoint and device-level security
• Supports regulatory compliance and internal audits
• Enables more thorough, credentialed scanning with full system access

Common use cases:

• Routine checks in high-compliance industries
• Post-breach investigations
• Remote or hybrid workforce endpoint validation
• Infrastructure updates and system expansions

External vulnerability scanning focuses on your publicly exposed assets—what an attacker sees from the outside. These scans are often used to simulate external threats and find vulnerabilities before hackers do.

Key benefits:

• Detects risks in websites, firewalls, and public-facing applications
• Helps reduce exposure to phishing, DDoS, and malware attacks
• Enhances security posture by highlighting external weaknesses
• Supports penetration testing and third-party risk assessments

Common use cases:

• Launching new services or platforms
• Ongoing perimeter security monitoring
• Vendor and customer trust building
• Compliance reporting and certification readiness

Together, internal and external scans give you the best chance of finding—and fixing—vulnerabilities before attackers can exploit them.

Why You Need Both

We recommend running both external and internal vulnerability scans for a complete picture of your infrastructure’s security posture. They each cover different, crucial aspects of the same procedure – scanning your network and devices for weaknesses that may be easy to exploit.

External vulnerability scans help you to “lock the door” more effectively and to prevent hacks and malicious attacks from occurring in the first place. Internal scans, meanwhile, give you added protection “behind the door” – you’re effectively tightening up what attackers could access should they break into your systems.

What’s more, internal scanning assesses different types of threats. Unlike external scanning, internal tests ensure that bad actors from inside your company are taken care of. On top of all this, both methods use different scanning tools and techniques.

Choosing the Right Vulnerability Scanning Solution: Key factors to consider

When choosing a vulnerability scanning solution to suit your company’s security needs, you’ll need to consider:

• Whether you can try before you buy: Is there a trial option available?
• How often the scanner allows you to run tests: Can you scan quarterly, monthly, or at custom intervals?
• Your company’s size: Is the technology offered capable of scanning larger networks and data silos, or is it best suited for smaller operations?
• Does the scanner help you adhere to compliance standards?: For example, can it help you protect card data in line with PCI DSS requirements?
• What types of vulnerabilities can your tool scan for?: Is it credentialed or unauthenticated? Does it specialize in surface-level scans or deeper analysis?
• How are reports delivered?: Can you access real-time scanning data? How thorough are the reports you receive?
• Are there other services offered by the scanning developer?: Can you access penetration testing, threat detection tools, and on-demand help from the same team?
• Can you ask for help at any time?: How available and supportive are the developer’s customer care teams?

Regardless of your company’s size, compliance demands, or even where you are in your cybersecurity journey, VikingCloud is on hand to offer extensive vulnerability scanning support. We want to help you become better prepared against evolving threats – and the best way to get started is by running internal and external scans with a reputable team of experts.

Get in touch with our team now for more information, and to book a free consultation at your convenience.