Identify a weakness of a perimeter-based network security strategy to protect an organization's endpoint systems.

The fundamental weakness of a perimeter-based security strategy is its reliance on the "castle-and-moat" concept, which establishes a boundary between a "trusted" internal network and an "untrusted" external network. This model inherently assumes that any device or user already inside the perimeter is trustworthy. Consequently, if an attacker successfully breaches the perimeter (e.g., via a phishing attack on an endpoint or a compromised device brought onsite), they can often move laterally within the internal network with minimal resistance. This implicit trust in internal endpoints is the model's primary flaw, as it fails to protect against insider threats or threats that have already bypassed the initial defenses.

A. Modern perimeter defenses, such as Next-Generation Firewalls (NGFWs), are specifically designed with capabilities like threat intelligence and application identification to detect and block command-and-control traffic.
B. This statement describes the core principle of a Zero Trust architecture, which is the direct opposite of a perimeter-based strategy that implicitly trusts internal devices.
D. A primary function of a perimeter firewall is to monitor and enforce policy on all network ports. While misconfigurations can occur, the strategy itself is not inherently incapable of this.

1. National Institute of Standards and Technology (NIST). (2020). Zero Trust Architecture (NIST Special Publication 800-207).

Section 1.2

Background

Page 2: "Perimeter-based network security has also been shown to be insufficient since once an attacker breaches the perimeter

further lateral movement is much easier... This has led to the development of the zero trust security model

which assumes that a breach is inevitable or has likely already occurred." This directly highlights the weakness of trusting the internal network post-breach.

2. Palo Alto Networks. (n.d.). What Is a Zero Trust Architecture?

Section: "What Is Wrong with the Traditional Security Model?": "The traditional security model... is built on the concept of 'castle and moat.' In this model

it is hard to obtain access from outside the network

but everyone inside the network is trusted by default... The problem with this approach is that once an attacker gains access to the network

they have free rein to move around inside." This explicitly identifies implicit internal trust as the core problem.

3. Rose

C.

& MIT Staff. (2016). 6.857 Computer and Network Security

Lecture 15: Network Security. MIT OpenCourseWare.

Slide 10

"Firewalls: The castle model": This lecture material describes the perimeter model's limitations

stating

"Once you're in

you're in... Insiders are a huge threat." This supports the concept that the model's weakness is its trust in internal entities.