What Happens When the Threat Is Already Inside?
Effective internal network penetration testing addresses a classic security fear, much like the line from horror films: 'The call is coming from inside the house'.
In cybersecurity, this is a daily reality. While we spend a lot of time building strong walls to keep attackers out, many of the most damaging breaches happen after an attacker gets inside.
According to IBM's 2024/2025 Cost of a Data Breach Report, breaches caused by an 'insider', whether a malicious employee or a criminal using stolen credentials, are often the most expensive.
This is why internal network penetration testing is a non-negotiable part of a modern cybersecurity strategy.
What is Internal Network Penetration Testing?
It’s a security audit that simulates an attack from within your network. The test assumes the attacker has already bypassed your external defences.
This 'assumed breach' model asks an important question: 'If an attacker (or a rogue employee) gets a foothold on our network, what damage can they do?'
The goal is to find out how easily an intruder to move around, escalate their privileges, and steal your most sensitive data, your 'crown jewels'.
Common Internal Threats and Vulnerabilities
An internal network penetration testing audit looks for a different set of flaws than an external one. Once inside, an attacker is looking for easy targets and weak controls that allow them to expand their access.
Weak Access Controls and Permissions
This is a very common internal weakness. An employee in marketing might have access to sensitive financial servers, or a standard user account might be able to access administrator tools.
An internal network penetration testing expert will find and exploit these permission flaws.
Unpatched Internal Software
Many organisations are diligent about patching their external servers, but forget about internal software. An attacker who gains access to one laptop can use a known vulnerability to take over an entire server. We call this 'lateral movement'.
The ENISA Threat Landscape 2023 report highlights how attackers thrive in this environment. It identifies exploiting known vulnerabilities and compromising credentials as go-to tactics. Once inside, an attacker uses these weaknesses to move laterally and deploy ransomware, the prime threat.
An internal pentest directly searches for these unpatched systems and weak credentials to stop that lateral movement before it leads to a full-scale ransomware attack.
Poor Network Segregation
- Can your guest Wi-Fi network talk to your employee network?
- Can your development environment access your live production database?
If your network is 'flat' (meaning everything can connect to everything else), it makes an attacker's job much easier.
The Internal Network Penetration Testing Methodology
Our internal network penetration testing methodology is all about expansion and escalation. Think of it as a comprehensive checklist to find internal blind spots. We follow a clear path, outlined by EU frameworks.
Step 1: Initial Access (Simulated)
The test begins by giving our expert a 'foothold'. This is typically a standard user account and a connection to the network, simulating either a compromised employee laptop or a malicious insider.
Step 2: Internal Reconnaissance
From this starting point, the expert scans the internal network. They look for other computers, file shares, servers, and databases. The goal is to map the internal landscape and identify high-value targets.
Step 3: Lateral Movement and Privilege Escalation
This is the core of the test. Our pentest expert will try to move 'laterally' from their initial foothold to other systems.
They’ll try to steal credentials, exploit unpatched software, and find misconfigurations that allow them to escalate their privileges. The goal here is to become a 'Domain Admin' with complete control of the network.
Step 4: Reporting and Your Remediation Checklist
Finally, we demonstrate the impact. We show how we gained access to your sensitive data (without actually stealing it) and provide a clear report. This report maps out the exact path we took and gives your team the actionable steps needed to close these internal pathways.
The Benefits of Internal Network Penetration Testing
Your external defences will, at some point, fail. A user will click a phishing link, or a new 'zero-day' vulnerability will appear.
Internal network penetration testing is your insurance policy for that event.
It tests your 'defence-in-depth'. It checks if your internal controls, like network segmentation and access policies, are actually working.
The main benefit of internal network penetration testing is building a more resilient network that can contain a breach before it becomes a catastrophe.
The 7ASecurity Approach: Simulating a Real Insider
At 7ASecurity, we specialise in manual security audits that mimic a cybercriminal. Our internal network penetration testing service simulates a real, determined insider.
We don’t just run a scanner. Our experts manually hunt for the hidden pathways and permission flaws that automated tools can’t see. We find the route to your 'crown jewels' and show you exactly how to block it, all backed by our free fix verification service.
Internal Network Pentesting FAQs
Why do I need an internal test if I trust my employees?
An internal network penetration test isn't just about rogue employees. It primarily simulates what happens after an attacker steals an employee's credentials via a phishing email. It tests your ability to contain a breach once it’s inside your perimeter.
What do you mean by 'lateral movement'?
'Lateral movement' is how an attacker, after compromising one computer (like a laptop), moves 'sideways' through your network to find more valuable targets.
They might jump to a file server, then to a database. Our test is designed to find and block these pathways.
Is this test done on-site or remotely?
This can be done either on-site or, more commonly, remotely. We typically simulate an attacker by connecting to your network via a secure device or VPN, providing the same access as a compromised employee machine.
My external network is secure. Is this still necessary?
Yes, absolutely. This is a fundamental part of a 'defence-in-depth' strategy, which is necessary for robust security and compliance. It assumes your perimeter will, at some point, be breached.
This test verifies that your internal controls are strong enough to contain that breach and protect your critical data.
Secure Your Network from the Inside Out
Perimeter security is only half the battle. To truly protect your organisation, you must be just as strong on the inside. 7ASecurity provides the deep-dive, expert-led testing you need to secure your data from all angles.
Find your internal blind spots.
