11 Ways Hackers Find Vulnerabilities in

Websites And How to Stay Ahead

Most websites don’t get hacked because someone “picked” them. They get hacked because
an automated system scanned thousands of sites, found an easy weakness, and moved in.
That weakness might be an old plugin, a forgotten subdomain, a test page left online,
or a simple misconfiguration.

Understanding how hackers find vulnerabilities in websites is one of
the most effective ways to protect your own. You don’t need to learn how to attack a site
– you just need to understand where attackers look, what they care about, and how they
decide which websites are worth their time.

“Hackers don’t start with magic tricks. They start with information.”

In this guide, we’ll walk through 11 common approaches attackers use to discover
weaknesses in websites, in language that business owners, developers, and
technical managers can understand. We’ll focus on:

• What attackers typically do
• What they are trying to find
• What risks each method creates for your site
• How you can stay one step ahead – without turning into a hacker yourself

The perspective here comes from real-world audits and penetration tests performed by
security teams like Codeila,
where the goal is always the same: find problems before an attacker does.

Quick Overview: How Attackers Look for Weaknesses

Before we dive into each method, here’s a simplified overview comparing the main
approaches hackers use and what you should be doing in response:

Now let’s look at each of these in more detail – from an attacker’s perspective and from
yours.

1. Internet-Wide Scanning: Finding Easy Targets at Scale

Most attackers don’t start with your brand name. They start with a big picture of the
internet: IP ranges, hosting providers, and technologies. With scanning tools and cloud
infrastructure, they can probe millions of IPs and domains in hours.

“From an attacker’s point of view, the question isn’t ‘who to hack’ but ‘what’s vulnerable
right now’.”

What They Actually Do (High Level)

Without going into harmful detail, the idea is simple: they run automated scanners that:

• Check which ports are open (web servers, databases, remote access)
• Identify which services run on those ports
• Grab “banners” that reveal versions or software names
• Tag targets that look outdated or misconfigured

If your server exposes more than it should, you move from “random IP” to
“interesting target”.

What This Means for You

• Close all ports you don’t actually need exposed to the internet
• Put your website behind a reputable WAF / reverse proxy (e.g. Cloudflare)
• Disable unnecessary services and panels from public access
• Keep your web server and OS regularly patched

If you’re unsure whether your exposed services are safe, a professional security
assessment from a team like
Codeila
can map your attack surface and highlight risky entry points.

2. Fingerprinting Your Tech Stack: “What Is This Site Running?”

Once attackers know your website is online, the next question is:
what is it built on? The answer matters because different technologies
have different well-known weaknesses.

What Attackers Try to Learn

• Are you using WordPress, Joomla, Drupal, Magento, Laravel, etc.?
• Which version of your CMS or framework is running?
• Which plugins and themes are visible from the outside?
• Which JavaScript libraries appear in your page source?

They don’t need full access to find this information. Small clues in HTML, HTTP
headers, file paths, and resource names often reveal a lot.

“Every version number you expose is effectively an invitation to check for known bugs.”

How You Can Stay Ahead

• Update your CMS, plugins, and themes promptly
• Avoid exposing obvious version numbers in page footers or headers
• Remove unused plugins and themes completely (not just deactivate)
• Use a security plugin or WAF that hides or normalizes some stack details

You don’t have to hide everything, but you shouldn’t hand out a complete
“technology inventory” to anyone who visits your homepage.

3. Matching Your Site Against Public Vulnerability Databases

Once attackers know what you’re running, the next step is straightforward:
check whether your software has known vulnerabilities.

Public databases like the
NVD (National Vulnerability Database)
and community resources such as
CVE Details
list thousands of known security flaws in plugins, themes, frameworks, and libraries.

Attacker’s Thought Process

The logic looks something like this:

• “This site runs Plugin X version 1.2.3.”
• “Version 1.2.3 has a known vulnerability from 2023.”
• “The patch was published months ago.”
• “If they never updated, there’s a good chance the hole is still open.”

At that point, the site becomes a very attractive target.

What You Should Be Doing Instead

• Track security advisories for your CMS and major plugins
• Apply security patches as soon as realistically possible
• Replace abandoned plugins/tools with actively maintained alternatives
• Schedule regular “update and review” cycles, not one-time cleanups

Professional vulnerability scanning and penetration testing, like those provided by
Codeila,
mirrors this process – but with the goal of fixing the issues instead of abusing them.

4. Hunting Forgotten Subdomains and Staging Sites

It’s common for companies to have more than just www.example.com. Over time,
they add:

• dev.example.com
• staging.example.com
• old.example.com
• panel.example.com
• cp.example.com

Some of these get forgotten, left unpatched, or even abandoned. For attackers, these are
gold mines.

“Attackers love the parts of your infrastructure you forgot existed.”

What Attackers Look For

• Old CMS installs with no updates
• Test or demo environments using real data
• Exposed admin panels (control panels, phpMyAdmin, etc.)
• Tools meant only for internal use but left open

How to Defend Against This

• Run regular DNS and subdomain audits
• Remove or properly protect staging/dev environments
• Never use production data in test environments visible online
• Put internal panels behind VPN or IP restrictions

A comprehensive security review should always include subdomains – not just
the main site sitting on www.

5. Probing Exposed Admin and Login Pages

When attackers find an admin panel or login page, they don’t always try to “hack” it
immediately. First, they observe how it behaves:

• Does it leak any error messages?
• Does it support multi-factor authentication?
• Are there obvious rate limits on failed logins?
• Does the URL suggest what software it belongs to?

Typical Targets

• /wp-admin / /wp-login.php (WordPress)
• Vendor-specific admin panels (cPanel, Plesk, custom dashboards)
• Login portals for clients or staff

“An unprotected login page is like a door that invites the whole world to try keys on it.”

What You Can Do

• Restrict admin access by IP whenever possible
• Enforce strong passwords and 2FA on all privileged accounts
• Limit login attempts and add timeouts for repeated failures
• Hide or rename standard login URLs where applicable

You don’t need to make your site invisible; you just need to make attacking it expensive
and unattractive compared to weaker targets.

6. Testing Inputs and Forms for Weak Validation

Any place where users can submit data – forms, search boxes, upload fields, feedback
widgets – is a potential entry point. Attackers know that rushed code and legacy
features often forget strict validation.

What They Experiment With (Conceptually)

At a high level, they:

• Observe how the application responds to unusual input
• Watch for error messages that reveal database or framework details
• Look for signs that input isn’t sanitized properly
• Check file upload forms for weak checks on file type or size

The goal is to find places where they can push the application beyond what developers
expected – sometimes leading to injection, file upload abuse, or authentication bypass.

How You Should Respond as a Site Owner or Dev

• Adopt secure coding practices (parameterized queries, escaping, validation)
• Use server-side validation – not just JavaScript checks
• Limit what types of files can be uploaded and where they are stored
• Use a WAF to add an extra layer of protection on common attack patterns

If your site handles sensitive data, periodic application security testing is essential.
That’s where a professional security partner like
Codeila’s team
can simulate how attackers would poke at your forms – but with the intent of fixing
problems rather than exploiting them.

7. Reusing Leaked or Weak Credentials

One of the simplest – and sadly most effective – ways attackers break into websites is by
trying passwords that were already leaked somewhere else.

“Most people don’t get hacked because their password is guessed. They get hacked because
they reused a password that was already stolen.”

How It Plays Out

Over the years, many large platforms have suffered data breaches. Those breaches leak
email–password combinations. Attackers collect and organize them. Then they:

• Try the same combinations on other websites and admin portals
• Exploit the fact that many people reuse credentials across services

What You Must Do to Reduce This Risk

• Enforce strong, unique passwords for all admin and privileged accounts
• Enable 2FA so a password alone is not enough
• Encourage staff to use password managers instead of reusing passwords
• Monitor for suspicious login activity and unusual locations

It’s also wise to periodically check whether your own email addresses have appeared in
known breaches using reputable services such as
Have I Been Pwned.

8. Exploiting Misconfigurations and “Low-Hanging Fruit”

Not every weakness is a complex bug. Some of the most damaging incidents start with
something simple:

• Directory listing left enabled
• Backup or .zip files stored inside the web root
• Debug pages visible in production
• Old installers left accessible
• Default passwords never changed

How Attackers Take Advantage (Conceptually)

They try predictable paths, test for exposed listings, and look for files that clearly
don’t belong in a polished production site. If they find something like
backup-old-site.zip or db.sql, things can go very wrong
very quickly.

How to Clean This Up

• Disable directory listing on your web server
• Store backups and exports outside the web-accessible root
• Remove installers, test scripts, and debug pages from production servers
• Change default passwords everywhere (routers, panels, admin tools)

A security hardening review often finds these misconfigurations faster than any
“vulnerability scanner” because it combines tools with experience and a critical eye.

9. Targeting Third-Party Integrations and APIs

Modern websites don’t live in isolation. They are connected to:

• Payment gateways
• CRM systems
• Email marketing tools
• Analytics services
• Custom APIs and microservices

Each integration potentially introduces another place where security can break down.

“Your security is only as strong as the weakest system you trust with your data.”

Where Things Often Go Wrong

• API keys embedded in frontend code
• Webhooks that accept unauthenticated requests
• Third-party plugins that are poorly maintained
• Overly broad permissions granted to connected apps

How You Can Strengthen This Area

• Review which third-party tools have access to your data and admin functions
• Rotate API keys regularly and never expose them in public code
• Implement proper authentication on webhooks and callbacks
• Give third-party systems the minimum permissions they truly need

Regular audits by an external security team can help you spot integration risks you
might not notice from inside your own environment.

10. Using Open-Source Intelligence (OSINT) Against You

Attackers don’t always start with your server. Sometimes they start with Google,
LinkedIn, GitHub, job posts, presentations, or old documentation. This collection of
publicly available information is often called OSINT (Open-Source Intelligence).

What They Learn Without Touching Your Site

• Which technologies your company prefers (from job listings)
• Which cloud providers and regions you use
• Which internal project names or URLs have been mentioned before
• Which staff members might have elevated access

None of this is a direct “attack,” but it helps shape a more targeted strategy against
your website and infrastructure.

How to Reduce OSINT Risk

• Avoid oversharing infrastructure details in public materials
• Sanitize screenshots before posting them
• Train staff to be careful about technical details they publish
• Periodically search your own name, brand, and domains to see what’s out there

You can’t remove every trace of information, but you can avoid giving away an easy roadmap
to your internal systems.

11. Manual Deep-Dive by Skilled Attackers and Researchers

Automated tools and quick scans catch a lot – but not everything. The most serious,
high-impact issues are often discovered by skilled security researchers who take the
time to understand how your specific website and business logic work.

“Complex vulnerabilities often live in the spaces between features, not in a single file.”

What This Looks Like (At a High Level)

Instead of blindly poking at forms, a skilled attacker or ethical tester will:

• Map out how your application works from start to finish
• Trace how data moves between pages, APIs, and databases
• Look for assumptions developers made that might not always hold true
• Check how the system handles edge cases and errors

This is how subtle logic flaws, privilege escalation paths, and chained vulnerabilities
are often found.

Why You Need Professionals on Your Side

The same deep-dive mindset that advanced attackers use can be used defensively by
professional penetration testers. The difference is intent: they document and help fix
what they find instead of exploiting it.

A mature security strategy usually includes:

• Secure development practices from the start
• Regular code reviews
• Automated security testing in CI/CD pipelines
• Periodic manual penetration tests by experts

This is the space where experienced teams like
Codeila
can add significant value, combining tools, methodology, and human analysis to
protect your site.

Putting It All Together: Think Like a Defender, Not a Hacker

You don’t need to become an attacker to protect your website, but you do need to stop
seeing security as a one-time checkbox. Attackers:

• Scan constantly
• Exploit old vulnerabilities that people never patched
• Take advantage of forgotten subdomains and misconfigurations
• Abuse weak passwords and leaked credentials
• Chain together small weaknesses into serious breaches

Defenders, on the other hand, need to:

• Keep software and infrastructure up to date
• Minimize what is exposed publicly
• Harden configurations and remove “junk” from production
• Treat third-party integrations as part of the attack surface
• Invest in regular assessments, not just emergency responses

“Security is not about making your website impossible to hack. It’s about making it
a far less attractive target than the thousands of easier options out there.”

Understanding how hackers find vulnerabilities is the first step. Acting on that
understanding – updating, hardening, testing, and monitoring – is what keeps your
website, your data, and your customers safe.

Need Help Finding Your Own Weak Spots Before Someone Else Does?

If you want a serious, human-led security assessment of your website – including
vulnerability analysis, controlled exploitation, and clear remediation guidance – the
security team at Codeila
can help.

Whether you run an online store, a SaaS product, or a company website that you simply
can’t afford to lose, a professional penetration test is one of the most effective ways
to stay ahead of attackers.

Want to see where your website could be vulnerable before hackers do?
Reach out now via our contact page:
https://codeila.com/contact/