When most people picture a cyber attack on a factory, power plant, or oil and gas facility, they imagine elite hackers using sophisticated tools in some dark room. That does happen. But in reality, the way attackers get in is usually far more ordinary. Someone reuses a simple password. Someone clicks a fake email that “looks legit”. Someone plugs an unknown USB into a machine near a control system. Someone turns off a safety control “just for today” to get the job done faster. In OT environments, these “small mistakes” are not small. They can stop production, damage equipment, or even put lives at risk. In one survey of OT professionals, almost 80 percent said human error is the biggest threat to OT control systems. So yes, tools, firewalls, and monitoring matter. But if you ignore the human sitting at the screen, you are basically leaving the front door wide open

Human Mistakes Hurt More in OT Than in IT

In a typical IT environment, a bad click or a wrong configuration usually means data is lost, systems go down, or money is lost. That is serious, but it stays in the digital world. In OT, the same kind of mistake can have real physical consequences. It can damage equipment and put people at risk. Examples include: A production line stopping

Power going out for thousands of people

Valves failing to close

Safety systems not activating

Most OT equipment was built to keep processes running reliably and easily. Security was not a priority. Many industrial control systems were designed decades ago and were only later connected to corporate networks and the internet. This connection increased the attack surface while leaving old weaknesses in place.

Add human error on top of that and you get a fragile environment where one small mistake can trigger serious physical problems

The Main Types of Human Error in OT

Human mistakes are often the easiest way for attackers to gain access or create risk in operational technology environments. Here are the most common ways this happens.

1. Falling for Social Engineering and Phishing

Attackers do not always target control systems directly. They target people. Emails may appear to come from vendors, government agencies, or internal departments. A hurried engineer might open an attachment or log in to a fake portal. That small action gives the attacker a foothold in the network. Cybersecurity studies show that a large portion of breaches involve human errors like clicking malicious links, opening fake attachments, or mishandling data. In OT environments, that single mistake can allow an attacker to move from an office system into a plant network that was never designed to face such threats.

2. Weak Password Practices and Poor Access Control

Many industrial sites still rely on default passwords, shared accounts, or reused passwords across multiple systems. Contractors and staff sometimes share logins because it is "easier for operations." For attackers, this is ideal. Stolen credentials can give access to multiple systems. Surveys consistently show that misused employee credentials are among the top causes of data loss and security breaches. In OT, compromised credentials can provide access to: Human machine interfaces

Engineering workstations

Remote access servers connected to control networks

3. Misconfiguration and Rushed Changes

Engineers and technicians face constant pressure to keep operations running. Downtime is expensive, so speed often takes priority over security. This can lead to: Firewalls opened temporarily and never closed

Remote access left always on for vendors

Safety or security alarms muted because they trigger too often

Patches and updates delayed for months or years

These actions are not malicious. They are practical decisions made under pressure. But they create fragile systems where a single error or attacker can cause serious damage.

4. Lack of Awareness About OT-Specific Threats

Many plant staff still treat cybersecurity as an IT issue. They may follow basic rules like “do not plug in unknown USBs” or “avoid pirated software,” but they often do not realize attackers now target control systems directly.

Real-world examples include malware like Stuxnet, which damaged equipment in an Iranian nuclear facility, and Industroyer, which was used against the Ukraine power grid.

Without awareness of these threats, staff may underestimate how small shortcuts or changes can create major risks.

When Human Error Hits OT

Here is how human mistakes can turn into real-world problems. A technician plugs a laptop used at home into a programmable logic controller without proper checks. The laptop carries malware straight into the control network. A control room operator sees fake alerts because attackers have tampered with data. Acting on incorrect information, the operator takes actions that put the plant in an unsafe state. A manager prioritizes uptime above all else. Staff learn to take risky shortcuts and ignore security steps that are seen as “slowing things down.” Studies of OT environments show that human error contributes to a significant portion of unplanned manufacturing downtime, and attackers actively exploit these mistakes. The reality is simple: attackers do not always need a sophisticated exploit. They just need one tired, rushed, or careless person to make a mistake.

Why Training Alone Cannot Solve the Problem

The usual response to human error is to offer more awareness training. While training is important, it is not enough by itself. People forget, and a once-a-year slide deck cannot compete with daily routines and the constant pressure of operations. Culture matters more than knowledge.

Moreover, in environments where uptime is valued above everything else, staff are likely to ignore safe practices when they conflict with production goals. Operational technology is also very different from standard IT. Generic cybersecurity training rarely shows operators and engineers how attacks can affect real equipment, leaving them unprepared for the specific risks they face. The solution requires a combination of technical controls, human-focused measures, and strong process controls. Relying on any one of these alone will leave the system vulnerable

You Cannot Eliminate Human Error, But You Can Reduce Its Impact

Human error will always exist, but you can take steps to reduce how often it happens and how much damage it can cause. Practical measures can make a real difference.

First, make it difficult to do the wrong thing. Relying on people to remember rules is not enough. Systems should be designed to prevent dangerous actions wherever possible. This includes using separate accounts for administrative and normal tasks, enforcing multi-factor authentication for remote access, removing default passwords and requiring strong unique ones, and limiting which USB devices can connect to control network equipment. Any attempt to bypass these safeguards should trigger alerts and follow-up.

Next, segment and isolate OT networks. Many industrial networks are still flat, meaning once someone gains access, almost everything is reachable. Clear separation between office networks, control networks, and safety-critical systems is essential. Using network zones, firewalls, and strict communication rules makes it much harder for an attacker to move from a compromised office device into the control environment. Training should be specific to your plant. Generic online courses are not enough. Staff need to understand how phishing emails could cause a real plant incident, how malware on a vendor laptop could impact their specific control system, and how misconfigured firewall rules could affect their lines or units. Real examples and clear, simple stories help change daily habits, which is the ultimate goal. Culture matters as much as rules. If leadership constantly emphasizes “never stop production,” staff will cut corners. Leaders need to show that it is acceptable to slow down if something seems unsafe, that reporting mistakes early is valued, and that incidents will be analyzed to fix systems, not punish honest errors. A culture where people feel safe to speak up helps identify weaknesses before attackers do. Testing people and processes is critical. Regular exercises, such as phishing simulations, tabletop attack scenarios, and drills simulating the loss of key systems, reveal how the organization responds under stress. The goal is not to shame employees but to understand weaknesses and improve them.

The hard truth is this: you can invest in top firewalls, monitoring platforms, and polished cybersecurity policies, but if a tired engineer can still connect an infected laptop, if a vendor can log in with a shared default password, or if staff are afraid to stop a line when something feels wrong, your OT cybersecurity remains fragile. The weakest link is not the device. It is the behavior around the device. Treat human error as a core risk in OT, not an afterthought. Build technical controls, human-focused measures, and a supportive culture around this reality. Doing so reduces both the likelihood of an incident and the damage when something inevitably goes wrong.

About Author Muhammad Ali Khan ICS/ OT Cybersecurity Specialist - AAISM | CISSP | CISA | CISM | CEH | ISO27001 LI | CHFI | CGEIT | CDCP