How organisations can reduce the risk of internal IT security threats

Cyber and IT risks originating within organisations are becoming an increasing concern across all sectors. Insider threats are responsible for over 40% of data breaches, with half being malicious and half being accidental. 

In this blog post, we explore the common threats, real-life examples, and how companies can build business resilience from within.

What are internal IT security threats?

Internal IT security threats originate from inside, from users who have legitimate and trusted access to your network. These aren’t just employees, but also third-party partners, vendors, and contractors.  

These internal risks can be categorised as follows, each being equally catastrophic:

Human error or negligence

According to the Information Commissioner’s Office (ICO), 74% of all security breaches have a human element at the core. This could be anything from misconfiguring a database, using a recycled password, or falling for a sophisticated phishing attack. 

Malicious intent

Malicious intent is when an insider abuses their access privileges. This could be for multiple reasons, from personal gain to intentional sabotage due to a breakdown in the relationship with the employer. Examples of malicious intent include stealing intellectual property before leaving the company or leaking sensitive customer data.

Common threat types

There are a number of ways that internal systems can be left exposed, and we have listed the most common below. These may be accessed by negligent insiders, external actors using real credentials, or malicious insiders looking to cause deliberate harm to a company’s security frameworks.

Compromised credentials

This may be weak or reused passwords, lack of Multi-Factor Authentication (MFA), or password sharing. This allows attackers to log in to systems appearing as a trusted user.

Social engineering & phishing

Falling for email phishing, or Business Email Compromise (BEC) can result in a well-meaning employee becoming an accidental gateway for cybercriminals.

Shadow IT

Using personal cloud storage for work purposes, unauthorised AI tools, and unsecure messaging apps, can create hidden threats that internal IT security teams can’t monitor. Data that is stored outside company perimeters is a critical risk.

Unpatched software  

Employees who are negligent and leave workstations unlocked and critical system updates that are delayed can result in exploitable entry points.

Exposed legacy data

Leaving old documents on active servers or forgotten staging environments can allow sensitive data to be exposed indefinitely. 

Malicious data infiltration

Individuals who are disgruntled and already know where the most valuable data is kept, may act on this knowledge and steal IP addresses, download client databases, or sell credentials.

Real-life examples of internal IT security threats

When we talk about internal security risks, we aren’t just defending against malicious insiders; we are protecting against the everyday human workarounds and systemic oversights within our own networks. The following real-world cases illustrate how easily a single bypassed verification step or a forgotten legacy file can have fatal cyber security consequences. 

M&S supply chain attack

In April 2025, the Scattered Spider group used Marks & Spencer’s third-party service desk, Tata Consultancy Services, to deploy ransomware on M&S’s servers. They did this by impersonating an M&S employee and convincing a member of support staff at Tata to reset a password.  

Over 1,000 stores were affected, and online sales were shut down for several days, resulting in losses of roughly £3.8 million per day. Some customer data was also stolen, including partial payment information.  

This is a perfect example of how multi-factor authentication is essential throughout a supply chain. Stronger cyber security awareness training could have also prevented the infiltration.  

Ministry of Defence identity leak

In the same month as the M&S attack, the Sunday Times revealed that 20 members of the UK’s Special Forces (including SAS and SBS members) had details including names, ranks, and operational codenames, publicly available online through documents that had been internally published and were intended strictly for internal armed forces personnel. These had been hosted on an exposed server without password protection for over a decade.  

The Ministry of Defence (MoD) took immediate action to remove the documents, however, this identity leak exposed a failure of basic data management. Legacy PDFs and resources hosted on public domains can pose a serious risk. For internal teams, it is a reminder to establish automated content expiration and regularly audit access privileges. Old documents need to be removed or archived behind a secure firewall.

Taking a proactive approach to internal IT security threats

Proactive IT management is much more effective than waiting for an attack to happen. Shutting down external and internal threats before they occur requires both automated and human defences:

1. 24/7 continuous system monitoring  

Round-the-clock monitoring across your company’s systems alert your team to unusual behaviours, such as off-hour login attempts or batch file transfers.  

2. Watertight access management 

It is important to conduct regular audits of who has access to what, and delete legacy or idle accounts. The Principle of Least Privilege (PoLP) is a core security practice that limits users and systems to only the minimum access needed to do their jobs.

3. Automated updates

Cybercriminals commonly target unpatched vulnerabilities. By automating patch updates for operating systems and third-party applications, you can make sure that your defences are up-to-date year-round without burdening your team with this manual administrative task.

4. Clear security guidelines

Your company security policies need to be updated regularly and need to provide clear guidelines on password best practices, remote working configurations, and everything your staff needs to operate securely on a daily basis.

5. Regular cyber security training

At Net-Defence, one of our favourite turns of phrase over the past year has been “humans are the weakest link”. However, it’s also important to flip this on its head and view trained employees as your first line of defence. As our MD, Debra Cairns, reaffirms, “we wouldn’t let any employee begin work without proper training, so how can you expect them to protect your company from cyber attacks without it?” 
 
It can be difficult to strike the balance with training to prevent burnout or a checkbox mentality. A strong security culture that your team is actively engaged in looks like this: 

• Quick and digestible monthly training sessions on a single topic 

• Realistic and adaptive phishing simulations 

• Present real-life examples to explain how cyber threats can infiltrate day-to-day work processes 

By delivering lightweight, highly engaging training, you empower your employees to become proactive defenders without overwhelming their schedules or testing their patience.

How Net-Defence can strengthen your internal security

Now that you have a deeper understanding of internal threats, the real work starts in systematically defending against them.  

For many growing organisations, managing security, user access, and system updates internally can quickly become overwhelming. As an IT Managed Service Provider (MSP), we prioritise vigilance and availability.

Here is exactly how Net-Defence partners with your business to secure your user access, monitor your systems, and build an unbreakable foundation of cyber resilience: 

End-user support & access control

Your employees need seamless access to their data, but you need peace of mind that safeguards are active. We actively manage end-user devices to enforce the Principle of Least Privilege (PoLP) and secure user access.

Infrastructure monitoring & automated patching

We provide 24/7 remote monitoring and push critical security patches and software updates overnight to prevent vulnerabilities from being exploited, all backed by advanced anti-virus and Endpoint Detection and Response (EDR) management.

Backup and recovery

We provide encrypted, off-site backups with hourly cloud-based testing to prevent data loss. This acts as your operational safety net if recovery is needed.

Co-managed support

If you already have an internal IT department, we offer flexible, co-managed support models to act as an additional resource when your team needs it most. We can handle the day-to-day IT tickets and routine monitoring to free up your internal IT staff to focus on business growth.

Secure hosting

Whether migrating to the cloud (AWS/Azure) or utilising our dedicated, physical server facilities, we design highly available hosting architectures tailored to your compliance needs. 

With over two decades of experience, we combine strategic IT planning with hands-on technical expertise. Whether you need us to fully manage your IT environment or partner with your existing team, we tailor our service to fit your risk profile.

Building resilience from the inside out

Whether caused by a simple mistake or a deliberate abuse of access, internal IT security threats prove that the majority of attacks originate from the inside. As the real-world breaches at M&S and the Ministry of Defence demonstrate, a single bypassed verification step, a weak password, or a forgotten legacy file can have major consequences.