Immune Systems And Insider Threats: The Zero Trust Parallel

TK Keanini, CTO, DNSFilter.

Protecting an organization from insider threats requires complete clarity regarding the roles and duties of insiders. Armed with such clarity, defenders can implement a zero-trust approach in which each role receives only what’s necessary to perform that role. This core principle of least privilege echoes the complex biological systems and has proven highly effective.

There are many parallels in nature, but two stand out that show how zero-trust patterns mirror effective biological systems. The benefits are evident in terms of scalability, resilience and maintainability.

Parallel 1: Cellular Specialization—Nature’s Smart Security Design

Consider the human body. You have skin cells, heart cells and brain cells. Each type of cell has a specific job. A skin cell protects; it doesn’t pump blood—that’s the heart cell’s job. Nature gives each cell what it needs to do its job and nothing more. This is precisely what’s meant by least privilege in cybersecurity.

Think about growth: As a baby develops into an adult, the body adds more specialized cells. More heart cells make a bigger heart, but they still perform only the heart’s job. This allows complex organisms to scale without becoming chaotic and unmanageable.

Similarly, a zero-trust security approach lets companies grow smoothly. When new employees join or new systems are added, they get access only to what they need for their role. This keeps security manageable and strong, even as the company grows, preventing a chaotic access model that could lead to failure.

Resilience: Bouncing Back From Trouble

If you get a small cut on your skin, your whole body doesn’t shut down. The damage is contained to those skin cells. Because other cells have different jobs and are separate, they keep working just fine.

With zero trust, if one user’s account is hacked, the damage is limited. Because that account only had permission to access a small set of resources, attackers can’t reach everything. This keeps the business running even if one part is attacked.

Maintainability: Keeping Things Tidy and Fixable

When something goes wrong in the body—for example, an organ isn’t functioning correctly—doctors can often pinpoint the problem because functions are specialized. They know where to look.

In security, by giving everyone only the access they need for their job, zero trust makes systems easier to manage. It becomes simpler to check who has access to what, and if someone has the wrong access, it’s easier to spot and fix.

Parallel 2: The Immune System—Nature’s Vigilant Responder

The human immune system is a built-in security network. It’s constantly on the lookout for invaders such as harmful bacteria or viruses. But if it’s healthy, it doesn’t attack indiscriminately. First, it identifies whether something is a friend or foe. Only when a threat is confirmed does it launch a targeted defense. This verify, then act principle is a cornerstone of zero-trust security.

Scalability: Handling More Threats Without Confusion

As people encounter new germs, the immune system learns and adapts. It handles a vast number of threats because its defenders— antibodies and other cells—are specialized. It doesn’t collapse under “one more germ.” Instead, it creates a tailored response.

Businesses face a similar challenge. New employees, partners and applications are constantly added, each potentially needing access. Zero trust handles this growth by verifying every request before granting access. It doesn’t assume safety just because someone “got in once.” This allows companies to expand without creating wide-open systems where one mistake leads to large-scale compromise.

Resilience: Targeted Defense Without Harming The Host

When you get sick, a fit immune system attacks the germs, not healthy cells. Its precise response allows the body to recover. If it attacked everything, the harm would outweigh the illness.

Zero trust functions the same way. If an attacker gains access to one part of the network, they cannot move freely because each request requires new verification. This isolates the threat, preventing it from spreading and taking down the entire business.

Maintainability: Clear Rules For Access

The immune system has rules for identifying threats. While complex, its checks and balances enable consistent decisions for protection.

Zero trust relies on explicit rules: Trust no one by default, verify everyone and everything and grant only the minimum access needed. This clarity makes management easier. When a security issue occurs, it’s simpler to see which rule was broken and adjust, rather than untangling an overly broad access model.

Low Privilege, High Security

A skin cell isn’t meant to do a heart cell’s job. Each part of the body, like each part of a business, has a distinct function. Just as the body relies on specialized systems to stay secure, organizations need the right tooling and the culture to create a zero-trust architecture.

Businesses can learn from these biological principles when building cybersecurity programs. By applying least privilege, systems become not only more secure but also more manageable and resilient. This discipline must extend to every layer of the technology stack, especially foundational protocols that are often overlooked. An authentic zero-trust architecture trusts nothing by default, scrutinizing every request and connection relentlessly. That vigilance—inspired by nature’s own security design—is the hallmark of a defensible enterprise.

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