How Can You Secure Your IT When Working With Third-Party Contractors?

By: Eileen Smith on August 14, 2025

How Can You Secure Your IT When Working With Third-Party Contractors?

Business Continuity | Disaster Recovery | Compliance | Information Security

Small and medium-sized companies often hire contractors, vendors, and other third parties to perform services on premises such as electrical upgrades and HVAC repair.

An organization's infrastructure often overlaps or is interdependent with other systems within your building—think about the IT needed to support building controls or the climate control required to cool a server closet.

It’s common for companies to allow external contractors of all kinds access to privileged spaces within their buildings. But what happens when a third party damages your IT environment?

As a managed IT service provider, (MSP), we see this happen from time to time. Usually it’s due to normal human error, inadequate training, poorly managed IT getting in its own way, or insufficient supervision. Only rarely is it intentional or malicious.

That said, there are some simple steps you can take to minimize the chances of such incidents happening, and limit their impact when they do occur.

In this article, we’ll discuss the challenges SMBs face when allowing external parties to work on their IT or access key infrastructure to perform other work. We’ll examine some common ways your IT can be hurt by third parties and outline six effective measures to keep your business safe.

With this information, you’ll be able to develop a proactive strategy for safeguarding your IT hardware and systems and avoid accidental or intentional harm caused by third-party contractors.

What Risks Or Problems Can Happen Because Of Hidden Security Gaps?

Every time you open your systems, data, or physical premises to third-party agents (even ones you trust) there’s some risk, and your business can be adversely impacted.

Issues can range from minor inconveniences to full-scale operational shutdowns.

Here’s an example scenario:

An electrician installing a new 20-amp circuit steps on a loose network cable and takes down your Active Directory domain controller. An offline domain controller can disrupt your entire IT footprint. This includes broken access to domain resources like databases, servers, networks, and websites.

A major disruption such as this could lead to inadvertent data loss. Also, it might take a while to identify the root cause of the issue and restore service or access your data backups to retrieve the lost data.

Oftentimes, these are avoidable mistakes that occur because of an innocent error, inadequate training, or when a third-party agent is simply rushing to complete a job and accidentally damages your IT.

What Are Common Security Vulnerabilities That Can Increase Risks?

Third-party companies doing work on around your IT can cause unintended damage. There are several factors that can increase this type of risk to your business, including:

1. Improper or inadequate training

No two businesses are exactly alike. External service providers may be unaware of your specific IT access policies and procedures.

Contractors in fields like HVAC, plumbing or electrical are not expected to be knowledgeable about industry best practices or regulatory requirements when accessing, repairing, or modifying elements of their systems that integrate with your IT environment.

Neither are they familiar with the physical layout of your space or technology.

Without proper training or oversight, this can lead to inadvertent mistakes.

2. Budget constraints/staff shortages

Sometimes, these types of IT issues caused by third-party stakeholders are the result of business cost-cutting measures.

For instance, an organization knows that different vendors and third-party personnel occasionally have access to its technology, but the company fails to implement adequate security controls to protect it.

Deferred IT maintenance, a lack of robust physical and cybersecurity safeguards, and the use of outdated IT could increase the chances of something going wrong when bringing in outside contractors or third-party support.

Limited budgets can also mean having insufficient internal IT staff to regularly monitor the work of employees from outside companies while they’re accessing your equipment and systems. This could lead to some of the problems mentioned earlier.

Identifying a main point person to help oversee and monitor your IT when outside contractors are performing a job can help eliminate confusion and prevent issues. Using managed IT can fill this void by serving as an integral resource for internal and external stakeholders.

3. Lack of business continuity and disaster recovery (BCDR) planning

Let’s face it, with today’s rapidly changing business landscape, many small and medium-sized business leaders are so focused on dealing with day-to-day issues, putting out fires, and growing their business that they don’t have time to focus on the “what-ifs” of tomorrow.

However, failing to develop and implement a comprehensive BCDR plan could leave your company at risk in the event of an IT emergency triggered by the actions of an external company's personnel.

If you experience an unexpected outage or damage to critical equipment, you need to have a continuity and recovery plan in order to recover effectively.

What Are Effective Measures To Protect Your IT When Using Outside Companies?

There are a number of security solutions you can adopt to strengthen your security posture and safeguard your valuable IT assets. Those include:

1. Implement strong access controls

Give users the least amount of privilege possible in terms of access to network resources
Secure your devices, including network equipment, workstations, and other IT with strong authentication controls
Use network segmentation to restrict access to critical parts of your network to only authorized users

2. Limit physical access

Physically secure your infrastructure behind access-controlled doors
Physical security can include security monitors, physical barriers, alarms, doors with access codes, locks, security guards, and other resources
Provide a diagram of your building and IT infrastructure—including your on-premises network room or server room (with fobs or access keys to authorized individuals)—to familiarize external partners with your environment.
Only grant access to trusted parties. If you don’t know the person conducting the work, set clear boundaries for areas they can access and provide supervision.

3. Provide training

Provide any necessary training on your policies and procedures for using and accessing your IT hardware, software, applications, systems, and data.
This will help ensure that they follow the necessary protocols for securing your IT environment, and that they’re aware of any specific access or handling requirements to comply with state, federal, industry, or insurance cybersecurity requirements.

4. Do your due diligence

It’s critical when bringing in outside companies—particularly when working with individuals you don’t know—that you do your homework in researching them, including getting referrals from other customers when warranted.
This will allow you to compare companies to best match their services and expertise with your IT needs and business goals.

5. Develop a BCDR plan

Disaster can strike at any time. Whether it’s a natural disaster such as a hurricane or flood, equipment failure and data loss caused by human error, or a cyber incident, it’s critical that businesses develop a BCDR plan.
This plan will be your company’s blueprint for how your business will respond in the event disaster strikes to keep the doors open, and the steps needed to quickly recovery in its aftermath.

6. Review your insurance

Review your insurance policies to make sure you have sufficient coverage to protect you in the event of equipment failure, data loss, or other accidental or intentional damage to your technology caused by an external third-party.

Bottom Line: Securing Your IT From External, Third-Party Threats

After reading this article, you now understand

While no one can predict the future, having a plan and the right guardrails in place will help ensure that your business is prepared to face whatever challenges lie ahead.

Using a reliable managed IT services provider (MSP) can help you develop and implement a comprehensive security strategy and IT budget to meet your short- and long-term business goals.

While we know managed IT isn’t right for everyone, if you have decided to partner with an MSP, we recommend that you research several providers to find the one best suited for your business.

As a trusted local managed IT services provider, Kelser has helped hundreds of companies over our more than 40-year history find and remediate hidden security vulnerabilities to help keep them running smoothly, efficiently, and securely.

If you need help identifying vulnerabilities with a gap analysis, closing security gaps, developing and implementing a BCDR plan, or have other security or IT concerns, reach out by clicking the button. We're here to help.