What is an insider threat, and how to identify it

In 2024, the average cost of an insider threat incident reached $17.4 million.[1] When you consider that these types of incidents happen daily, it becomes clear that we’re facing a frequent and expensive danger. So, what is an insider threat? Today, it means much more than a data leak; it’s a strategic vulnerability that can disrupt business continuity.

What Is an Insider Threat in Cybersecurity?

In cybersecurity, the danger doesn’t always come from outside. Insider threats are security risks originating within the organization, caused by someone who works there or has authorized access to its systems and networks. These threats may be intentional or accidental.

According to the Cost of Insider Risks 2025 report, 55% of internal security incidents are caused by employee errors or negligence.^[2] What does that mean? You don’t need to plan a cybercrime to compromise a company’s security; sometimes, a single mistaken click is enough.

One of the biggest dangers of insider threats in cybersecurity is how easily they go unnoticed. Since the actors involved often use valid credentials, they don’t immediately raise red flags. How can these attacks be prevented? By strengthening internal policies, training employees, and implementing vulnerability management tools with proactive monitoring to detect suspicious activity from the inside.

Insider Threats in Action: Understanding Internal Risk Profiles

Spotting an insider threat isn’t always as straightforward as identifying an external hacker. Insider threat detection involves recognizing the different profiles that may pose a risk within the organization. From human error to calculated sabotage, understanding insider threat types is key to building an effective defense.

1. Intentional/Malicious Insider

These are deliberate actions carried out by current or former employees who are dissatisfied with the company. Motivated by this discontent, they may steal sensitive data, sabotage systems, or manipulate critical information. In some cases, they even collaborate with external actors.

These insiders are particularly dangerous because their actions are often well-planned and difficult to detect in time. They may wait for the right opportunity to exploit a system vulnerability, use social engineering techniques, or erase logs to avoid being caught.

In 2018, Tesla experienced a well-known malicious insider incident when a former employee was accused of sabotage.^[3] According to Elon Musk, the employee stole confidential data and modified the code of the manufacturing operating system.

2. Negligent Insider

This threat stems from mistakes or poor practices rather than malicious intent. Often the result of ignorance or carelessness, common examples include falling for phishing scams, overlooking security protocols, or misconfiguring systems.

In 2017, defense contractor Booz Allen Hamilton exposed over 60,000 sensitive files on an unsecured Amazon Web Services (AWS) server.[4] The data included classified information from the U.S. Army Intelligence and Security Command (INSCOM). 

3. Compromised / Third‑Party Insider

This category includes external users such as contractors, vendors, or former employees whose legitimate access has been hijacked. They function as insiders because they operate with valid credentials, making it easier to leak data or spread malware from within. In many cases, compromised insiders result from internal negligence.

In March 2025, Royal Mail suffered a massive data breach after attackers accessed its network through an external vendor, Spectos GmbH.[5] Using stolen credentials, they bypassed internal controls and exfiltrated over 144 GB of customer information, including personal data, internal recordings, and mailing lists.

Accepting that the threat may come from within requires a shift in how we approach security, toward a more human-centric, dynamic, and preventive model. Strengthening cyber resilience means going beyond just identifying threats. It involves rethinking assumptions about who poses a risk and why, and building a truly holistic security culture.

Internal Threat Indicators: Signs Worth Investigating

When someone with insider access launches an attack, they may need to hack internal systems or reconfigure hardware or software infrastructure. Recognizing the signs and tools involved is key to identifying insider risk and responding proactively.

Unusual Login Behavior

Most organizations follow predictable login patterns. Remote access from unusual locations or during off-hours can signal trouble. Authentication logs can also reveal strange username activity, like accounts named “test” or “admin,” indicating unauthorized access attempts.

Use of Unauthorized Applications

Critical customer and business management systems, as well as financial platforms, should be tightly controlled. These tools must have clearly defined user roles. Any unauthorized access to these applications, or to the sensitive data they contain, can be devastating to a business.

Privilege Escalation Behavior

People with higher-level system access pose an inherent risk. Sometimes, an administrator may begin granting privileges to unauthorized users, or even to themselves, to gain access to restricted data or apps.

Excessive Data Downloads or Transfers

IT teams must stay alert to their network’s regular bandwidth usage and data transfer patterns. Large, unexplained downloads, especially during odd hours or from unusual locations, may signal an internal threat.

Unauthorized Changes to Firewalls and Antivirus Tools

Any time firewall or antivirus configurations are altered, it could indicate insider tampering. These changes are often subtle attempts to weaken system defenses and create an easy path for future malicious activity.

The Threat Is Internal, but so is the Opportunity

Insider threats aren’t just technical failures; they reflect human dynamics, outdated processes, and gaps in security infrastructure. Building effective protection demands a proactive, evolving strategy, one that combines robust tools with prepared teams.

At LevelBlue, our simplified approach to cybersecurity with comprehensive managed security services helps organizations identify abnormal patterns, prevent unauthorized access, and respond to insider threats in real time. Our ecosystem of solutions enables continuous, agile defense, turning every threat into an opportunity for long-term improvement.

References
1. DTEX Systems. (2025, Feb 25). Ponemon Cybersecurity Report: Insider Risk Management Enabling Early Breach Detection and Mitigation.
2. DTEX Systems. (2025, Feb 25). Ponemon Cybersecurity Report: Insider Risk Management Enabling Early Breach Detection and Mitigation.
3. Mark Matousek. (2018, June 18). Elon Musk is accusing a Tesla employee of trying to sabotage the company. Business Insider.
4. Patrick Howell O’Neill (2017, June 1). Booz Allen Hamilton leaves 60,000 unsecured DOD files on AWS server. CiberScoop.
5. Check Red Security. (2025, April 14). When Trusted Access Turns Dangerous: Insider Risks in the Age of Third‑Party Vendors.

The content provided herein is for general informational purposes only and should not be construed as legal, regulatory, compliance, or cybersecurity advice. Organizations should consult their own legal, compliance, or cybersecurity professionals regarding specific obligations and risk management strategies. While LevelBlue’s Managed Threat Detection and Response solutions are designed to support threat detection and response at the endpoint level, they are not a substitute for comprehensive network monitoring, vulnerability management, or a full cybersecurity program.