Vulnerability Scanning
How Vulnerability Scanners Find Known Weaknesses
Vulnerability scanning is the automated process of testing a website or server for known security weaknesses, such as outdated software, risky settings and flaws listed in public vulnerability databases.
A scanner identifies the software a system runs, then compares the names and versions it finds against a database of published vulnerabilities, many of them listed as CVE identifiers. It also probes for open ports, default settings, exposed administration pages and weak encryption configurations. The output is usually a list of findings, each with a severity rating.
External and Authenticated Scans Compared
An external scan works like an outsider. It checks only what any visitor could reach, such as open ports and public pages. This shows the exposure an attacker sees first.
An authenticated scan logs in with credentials and checks installed components, package lists and configuration files from the inside. It usually produces more accurate results, because it can see software that is installed but not publicly visible. Authenticated scans require careful handling of the credentials they use.
The Limits of Automated Scanning
Scanners are useful but have clear limits. They can report problems that are not actually exploitable, which is called a false positive, and they can miss issues that do not match a known signature, which is a false negative. Custom code written for a specific website is often outside their view, so logic errors and design flaws rarely appear in a report.
A scan is also a snapshot. It reflects the system on the day it ran, and it cannot judge the business impact of a finding. Scanning is best treated as one part of a wider approach that includes patching, monitoring and manual penetration testing. Only scan systems you own or have clear permission to test.
Frequently asked questions
How often should a website be scanned for vulnerabilities?
Regularly, and also after significant changes such as a new plugin, a software update or a server migration. New vulnerabilities are published continually, so a scan that was clean last year may not be clean today. Scheduled recurring scans help catch new issues in software that has not changed.
Is a vulnerability scan the same as a malware scan?
No. A vulnerability scan looks for weaknesses that an attacker could exploit. A malware scan looks for malicious code that is already present. A site can pass one check and fail the other, so each serves a different purpose in keeping a site secure.