Why an Automated Scan Is Not a Penetration Test

Vulnerability scans are often passed off as penetration tests, or pentests for short. However, there is a significant difference between the two. This post explains what sets them apart and why you should not rely on vulnerability scans alone.

Vulnerability scans search for known weaknesses in systems and report potential exposures. Penetration tests, on the other hand, actively exploit architectural vulnerabilities to determine the extent to which an attacker can gain unauthorized access to your assets. A vulnerability scan is typically automated, while a penetration test is a manual engagement performed by a security expert.

A useful analogy: a vulnerability scan is like walking up to a door, checking whether it is unlocked, and stopping there. A penetration test goes further -- it not only checks whether the door is unlocked but also opens it and walks inside.

What Is a Vulnerability Scan?

A vulnerability scan identifies security weaknesses using specialized scanner software and classifies them according to their criticality.

A vulnerability scanner is a tool that automatically detects vulnerabilities and categorizes threats based on established assessment methods such as the industry-standard CVSS or well-known vulnerability databases. However, the raw output of a scanner is of limited value on its own, since it may contain false positives. The results therefore require subsequent analysis and validation by qualified personnel.

What Are the Types of Automated Scans?

There are three types of vulnerability scans, which can take anywhere from a few minutes to several hours depending on their scope: internal scans, external scans, and host scans.

Internal Scans

Internal scans aim to identify vulnerabilities within an organization's internal network. This may be a cloud network, a single network segment, a corporate network, or the entire network landscape comprising multiple networks (production, staging, corporate).

External Scans

External scans cover all components exposed to the Internet, including email servers, web applications, firewalls, portals, and websites.

Host Scans

Host scans target one or more specific hosts that serve as a database, web server, workstation, or fulfill another function.

What Is a Vulnerability Assessment?

A vulnerability assessment is a method for identifying and classifying threats that affect an asset -- such as a server, workstation, or network device. It helps organizations detect vulnerabilities using a scanner, then quantify and categorize them with the assistance of an experienced analyst, and ultimately mitigate the identified risks.

Vulnerability Assessment vs. Vulnerability Scan

The key difference: a vulnerability scan is the precursor to a full vulnerability assessment.

A vulnerability assessment involves running scans and compiling the results into a comprehensive list of weaknesses that affect your applications. This process is complemented by a security analyst's expertise in filtering out false positives and evaluating both the impact and the likelihood of potential attacks.

Make sure you do not purchase a basic vulnerability scan that is marketed as a full assessment. Only a genuine vulnerability assessment delivers an actionable risk evaluation for your organization.

What Is Penetration Testing?

In a penetration test, the tester behaves almost identically to a real-world attacker. That is precisely the strength of this approach: a pentest assumes the worst-case scenario -- a well-informed attacker deliberately attempting to breach your systems. The crucial difference from an actual attack is that vulnerabilities are exploited in a controlled manner with no adverse impact on your organization. Compared to a vulnerability assessment, the key distinction lies in the active exploitation of discovered weaknesses and the attempt to pivot further into the system. More information about pentests can be found here:

• Penetration Test

Vulnerability Assessment vs. Penetration Test

Vulnerability Assessment	Penetration Test
Identifying and documenting vulnerabilities using specialized scanner software	Identify, securely exploit and document vulnerabilities using automated tools and especially manual testing
Scaling based on the number of IP addresses/networks	Scale based on the criticality/functionality of the asset
More coverage, less depth	Deeper analysis

A vulnerability assessment is well suited for quickly obtaining a broad overview of vulnerabilities across your entire system landscape. A pentest, on the other hand, enables an in-depth analysis of individual assets.

How Do You Maximize the Security of Your Assets?

Given the ever-increasing risk of security breaches, running automated vulnerability scans on a regular basis is essential for any organization. However, even the most capable scanners cannot replace human expertise. They should therefore be combined with regular penetration tests, which uncover vulnerabilities that automated tools miss. Vulnerability scans do not replace penetration tests -- and penetration tests alone cannot secure your entire network.