Cyberattackers and hackers try to exploit security vulnerabilities to gain unauthorized access to enterprise networks. Their intentions typically include installing malware, stealing sensitive data, launching supply chain attacks, or engaging in cyber extortion or espionage.

As the cyber threat landscape expands, security experts at IBM believe that “thousands of new vulnerabilities (are) likely to be reported in both old and new applications and devices,” and conclude that the “risk surface will continue to grow in 2021.”

It’s imperative to protect your organization with network vulnerability assessments to discover and seal up those vulnerabilities. To do this, vulnerability scans are indispensable tools.

A vulnerability scanner is an automated vulnerability assessment tool that searches for, discovers, and reports on potential vulnerabilities in your organization’s IT infrastructure. You can then address these weaknesses before they lead to operational disruptions, downtime, security breaches, ransomware attacks, zero-day exploits, and other cyber events.

You can conduct either external or internal vulnerability scans with different types of scanners. An internal vulnerability scan operates within your internal network firewalls to identify at-risk systems and potential vulnerabilities inside the network.

In contrast, an external scan is performed outside your network. It looks for gaps in firewalls that may allow malicious outsiders to break in and attack the network and its assets. Like external penetration testing, external scanning can detect open ports and protocols. An external scan also looks at specific IP addresses to identify open, exploitable vulnerabilities that jeopardize network security.

Differences Between Internal and External Vulnerability Scans


Threats to the enterprise network can originate from both outside and inside the network. An external vulnerability scan looks into the network from outside to find, identify, and help close potential external entry points for unwanted intrusion. It starts by looking for weaknesses in the network’s firewall. It also tests the external network perimeter and outside IP addresses.

Conversely, an internal scan is designed to search the network’s internal components and find open vulnerabilities — that is, possible security gaps that bad actors may exploit.


An internal vulnerability scan takes an insider’s perspective: someone who has access to your enterprise network and systems. For example, a disgruntled employee may be a security risk. Hence the scan is performed internally, replicating typical access to the network being scanned.

On the other hand, an external scan takes an outsider’s perspective and is conducted without access to the network.

Common Vulnerabilities Detected

The most common vulnerabilities detected during internal scans include:

  • Missing third-party patches
  • Unpatched, high-risk known vulnerabilities
  • Common known vulnerabilities, such as vulnerabilities in open source software including the Heartbleed bug or the EternalBlue exploit

On the other hand, external vulnerability scans are beneficial for detecting:

  • The use of unsecured transfer protocols by various enterprise services
  • The use of deprecated services like TLS 1.0 or 1.1 to configure servers
  • Named vulnerabilities

Both internal and external vulnerability scans are critical to your business. They each have distinctive benefits defining their place in modern-day cybersecurity.

What Are the Benefits of Internal Vulnerability Scans?

Internal vulnerability scans look at the enterprise IT infrastructure and security profile from an insider’s viewpoint — specifically, someone who is authorized to access enterprise assets. This someone could be an employee or a third party such as a vendor or contractor.

By probing the IT infrastructure in that way, internal scanners and scans provide the following benefits:

  • Simulate the behaviors and actions of someone with standard privileges to identify vulnerabilities that could potentially impair business-critical systems, functions, and operations
  • Validate permissions and privileges with the respective access of insiders
  • Identify at-risk systems and prioritize vulnerability remediation
  • Provide useful insights to improve patch management and security management processes
  • Fix vulnerabilities to improve compliance with regulatory requirements or security standards such as HIPAA, PCI DSS, or ISO 27001/27002

You can perform either credentialed or non-credentialed internal scans. Credentialed scans reveal information about vulnerabilities that an outside attacker can exploit via a phishing attempt or malware.

Non-credentialed scans show what kind of network information a rogue in-house insider can obtain without the designated privileges. Both types of scanning processes can be beneficial for your organization since they expose different kinds of vulnerabilities and threats.

What are the Benefits of External Vulnerability Scans?

An external vulnerability scan is conducted from outside the enterprise network (that is, without access to the network). These scans target your network’s external IP addresses and detect open ports and protocols to identify security gaps.

Like internal scans, external vulnerability scans are proactive rather than reactive. That’s why these scans should also be a part of your cybersecurity program. They offer the following benefits:

  • Help verify the security posture of your externally facing services
  • Show known weaknesses in network structures that could lead to a breach
  • Reveal the most significant threats and risks in your enterprise network
  • Identify new devices or services that may present new threats or weaknesses to the enterprise

Make ZenGRC Part of Your Compliance System

ZenGRC provides a wide range of capabilities to help you streamline your vulnerability management program. It’s a single source of truth repository that features control frameworks, risk registers, customizable readymade templates, automation features, and built-in integrations.

Automated workflows document tasks and drive activities to completion. The ZenConnect feature enables integration with popular tools, such as Jira, ServiceNow, and Slack, ensuring seamless adoption across your enterprise.

Schedule a demo to see how ZenGRC empowers security teams to proactively identify threats and risks, protect the business, and minimize loss events.