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Website vulnerability testing is the process of scanning your website for security weaknesses that attackers could exploit. It covers SQL injection, cross-site scripting (XSS), open ports, directory traversal, insecure file uploads, default credentials, and misconfigured servers. Automated tools can test for 16+ vulnerability types in minutes.
Every website has weaknesses. Some are obvious, like an admin page accessible without a password. Others are subtle, like a form field that lets an attacker run database commands. Vulnerability testing is the systematic process of finding these weaknesses before attackers do.
It is not the same as a penetration test (often called a "pen test"), which simulates a real attack by an experienced security professional. Vulnerability testing is broader and more methodical: it scans for known issues across your entire website using automated tools, producing a prioritised list of problems to fix.
Think of it like an MOT for your website. You would not drive a car for years without checking the brakes, and you should not run a website without checking its security.
Automated scanners crawl your website, test every input field, check every header, probe every port, and compare what they find against databases of known vulnerabilities. A good automated scanner can test for 16 or more vulnerability categories in a single scan, completing in minutes rather than days.
Automated scanning is ideal for:
Penetration testing goes deeper. A skilled security professional manually explores your website, looking for logic flaws, business process vulnerabilities, and chained exploits that automated tools cannot detect. Pen tests typically take days or weeks and cost thousands of pounds.
For most small and medium businesses, automated scanning provides the best return on investment. It catches the vast majority of common vulnerabilities at a fraction of the cost. Manual pen testing is valuable for high-risk applications (payment processing, healthcare data, financial services) or as an annual deep-dive alongside regular automated scans.
A comprehensive vulnerability scan covers the OWASP Top 10, which represents the most critical security risks to web applications. Here are the main categories:
When your website takes user input (a search box, a login form, a URL parameter) and uses it directly in a database query without proper sanitisation, an attacker can inject SQL commands. This can let them read, modify, or delete your entire database.
Example: A login form where entering ' OR 1=1 -- in the username field bypasses authentication entirely.
XSS lets an attacker inject JavaScript into your web pages. When another user loads the page, the script runs in their browser and can steal their session, redirect them to a phishing site, or perform actions on their behalf. Read our detailed guide: What is cross-site scripting (XSS)?
CSRF tricks an authenticated user into performing actions they did not intend. An attacker creates a page that sends a request to your website using the victim's existing session cookie. If the user is logged in, the request succeeds.
Also called path traversal, this vulnerability lets an attacker access files and directories outside the intended web root by using sequences like ../../ in URLs or input fields. This can expose configuration files, password files, and source code.
If your website dynamically includes files based on user input (such as a URL parameter like ?page=about), an attacker might be able to include arbitrary files from the server or even remote files, potentially executing malicious code.
Similar to SQL injection, but instead of database commands, the attacker injects operating system commands. If your website passes user input to a shell command, an attacker can run arbitrary commands on your server.
Every open port on your server is a potential entry point. Ports that should not be publicly accessible, such as database ports (3306, 5432) or admin panels (8080), are routinely discovered by attackers scanning the internet. Read our guide: How to check for open ports on a website
If your website allows file uploads without properly validating the file type and content, an attacker can upload a PHP shell, a script, or other executable file and then access it directly to run commands on your server.
Many CMS platforms, admin panels, and databases ship with default usernames and passwords. Failing to change these is one of the most common and most easily exploited vulnerabilities.
Missing security headers, verbose error messages that reveal server details, directory listing enabled, default server pages visible. These are configuration issues rather than code vulnerabilities, but they make attacks easier.
A typical automated vulnerability scan follows this process:
Vulnerabilities are typically rated on a four-point scale:
Fix critical and high issues immediately. Medium issues should be addressed within days. Low issues should be scheduled into your regular maintenance.
The short answer: regularly. Security is not a one-time event. New vulnerabilities are discovered daily, and changes to your website (new features, updated plugins, server patches) can introduce new weaknesses.
Recommended schedule:
If your website is covered by GDPR (and if you operate in the UK or EU, it almost certainly is), you have a legal obligation to implement appropriate technical measures to protect personal data. Regular vulnerability testing is one of the most straightforward ways to demonstrate compliance.
A good vulnerability report should include:
PulseShield's free security scan produces exactly this kind of report, covering open ports, security headers, SSL configuration, cookie settings, email authentication, and more.
Get a free security report covering ports, headers, SSL, cookies, and email authentication for your domain.
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