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Insider Threat Matrix™Insider Threat Matrix™
  • ID: PV074
  • Created: 21st October 2025
  • Updated: 21st October 2025
  • Contributor: David Larsen

Network Segmentation

Network segmentation is a defensive architecture technique that restricts subject movement across enterprise infrastructure by logically or physically isolating systems into discrete zones. This is typically implemented using subnets, VLANs, firewall zones, and identity-aware access policies. In the context of insider threat, segmentation plays a critical role in constraining a subject's network visibility and access paths, even when they operate from a position of legitimate trust. By limiting lateral movement and enforcing strict boundaries between business functions, environments (e.g., development vs. production), and data classifications, segmentation reduces the risk of escalation, reconnaissance, or unauthorized data access. Effective segmentation requires technical enforcement at multiple layers (network, identity, endpoint), continuous telemetry, and alignment with organizational role structures.


Prevention Measures

 

Subnet-Based Segmentation
Use IP subnets to separate network segments by functional role (e.g., 10.10.10.0/24 for finance, 10.10.20.0/24 for development). Assign subnets according to department, data sensitivity, or risk profile, and apply routing controls between them using next-hop access policies or firewalls. Disable inter-subnet routing by default.

 

VLAN Isolation
Implement Virtual LANs to enforce broadcast domain isolation at Layer 2. VLANs should align with organizational trust boundaries—e.g., separate VLANs for HR, DevOps, guest Wi-Fi, and contractor endpoints. Switches and access ports should enforce 802.1Q tagging, and trunk ports must be tightly controlled to prevent unauthorized VLAN hopping.

 

Layer 3 ACLs and Route Maps
Apply router- or firewall-level Access Control Lists (ACLs) to explicitly permit or deny traffic between segments. Use route maps or policy-based routing (PBR) to enforce asymmetric flows or direct high-risk traffic through monitoring or decryption layers.

 

Host-Based Segmentation and Agent Policies
Deploy host firewalls or Endpoint Detection and Response (EDR) platforms capable of enforcing intra-host segmentation rules. Define policy-based isolation (e.g., deny RDP or SMB outside known ranges) and log all policy violations for cross-correlation with identity and behavior.

 

Zero Trust Segmentation
Extend segmentation beyond IP and port boundaries using software-defined per-session enforcement. Implement policy engines (e.g., Zscaler, Illumio, or Azure Firewall with Just-in-Time access) that grant access based on identity, device state, time, and justification, rather than static address rules.

 

Network Access Control (NAC) Enforcement
Integrate NAC (e.g., Cisco ISE, Aruba ClearPass) to dynamically assign VLANs or access profiles based on user role, device posture, or endpoint risk score. This prevents subject-controlled or unmanaged endpoints from reaching sensitive segments even if physically connected.

 

Firewall Zones and Traffic Inspection
Use next-generation firewalls to define security zones and inspect traffic at L7. Enforce inter-zone inspection with TLS decryption and application control policies to prevent tunneling, lateral file movement, or unauthorized data egress.

 

Logging and Alerting on Cross-Segment Access
Establish telemetry for segment-to-segment communication. Trigger alerts on:

  • First-time cross-subnet flows by user or host.
  • Failed connection attempts across segments.
  • Traffic volume anomalies between normally-isolated zones.


Correlate these with role-based access expectations and investigate for drift, reconnaissance, or misconfiguration.

Sections

ID Name Description
PR021Network Scanning

A subject conducts a scan of a network to identify additional systems, or services running on those systems.

ME028Delegated Access via Managed Service Providers

An organization entrusts a Managed Service Provider (MSP) with administrative or operational access to its digital environment - typically for IT support, system maintenance, or development functions. This access is often persistent, privileged, and spans sensitive infrastructure or data environments.

 

The means is established when MSP personnel, including potential subjects, are permitted to authenticate into the client’s environment from systems or networks entirely outside the client's visibility or jurisdiction. These MSP endpoints may be unmanaged, unmonitored, or physically located in regions where customer organization's policies, incident response authority, or legal recourse do not apply.

 

This creates an unobservable access channel: the subject operates from infrastructure beyond the reach of the customer organization's logging, endpoint detection, or identity correlation. The organization is therefore unable to monitor or verify who accessed what, when, or from where—rendering all downstream actions unauditable by the customer organization's internal security teams, unless mirrored within the client-controlled environment.

 

The exposure can be compounded by the MSP’s internal controls (or lack thereof). Weak credential custody practices, shared administrative accounts, inadequate background checks, or poor workforce segmentation create conditions where privileged misuse or unauthorized access can occur without attribution or immediate detection. The subject does not require escalation—they begin with sanctioned access and operate under delegated trust, often without the constraints applied to internal staff.

 

This structural dependency - privileged access held externally, without enforceable oversight - creates the necessary conditions for an insider infringement to occur with low risk of interruption or accountability.

ME024.006Access to Sensitive Organization Data

A subject with access to sensitive organizational data possesses the ability to view, retrieve, or manipulate information that is internally critical to the functioning, competitiveness, or integrity of the organization. This may include proprietary intellectual property, financial forecasts, internal audit reports, legal proceedings, incident investigation records, M&A materials, or internal threat detection logic. Access to such data is typically granted to personnel in roles including but not limited to finance, legal, security, compliance, research and development, or executive support functions.

 

While this data may not include customer information, its sensitivity is often equal or greater—particularly when tied to strategic decision-making, regulatory posture, or institutional trust. Misuse of access to sensitive organizational data can result in reputational harm, regulatory breach, loss of competitive advantage, or compromise of security functions. Because this access is frequently held by high-trust individuals or senior personnel, abuses may be harder to detect and more consequential in impact.

 

Unmonitored access to such data—particularly when permissions are inherited, overly broad, or poorly reviewed—can significantly elevate a subject's risk profile. This access may also attract external interest, such as social engineering attempts or recruitment by adversarial entities, making the subject a potential vector for external compromise.

ME024.003Access to Critical Environments (Production and Pre-Production)

Subjects with access to production and pre-production environments—whether as users, developers, or administrators—hold the potential to exploit or compromise highly sensitive organizational assets. Production environments, which host live applications and databases, are critical to business operations and often contain real-time data, including proprietary business information and personally identifiable information (PII). A subject with access to these systems can manipulate operational processes, exfiltrate sensitive data, introduce malicious code, or degrade system performance.

 

Pre-production environments, used for testing, staging, and development, often replicate production systems, though they may contain anonymized or less protected data. Despite this, pre-production environments can still house sensitive configurations, APIs, and testing data that can be exploited. A subject with access to these environments may uncover system vulnerabilities, access sensitive credentials, or introduce code that could be escalated into the production environment.

 

In both environments, privileged access provides a direct pathway to the underlying infrastructure, system configurations, logs, and application code. For example, administrative access allows manipulation of security policies, user permissions, and system-level access controls. Similarly, access to development environments can provide insights into source code, configuration management, and test data—all of which could be leveraged to further insider activity.

 

Subjects with privileged access to critical environments are positioned not only to exploit system vulnerabilities or bypass security controls but also to become targets for recruitment by external actors seeking unauthorized access to sensitive information. These individuals may be approached or coerced to intentionally compromise the environment, escalate privileges, or exfiltrate data on behalf of malicious third parties.

 

Given the sensitivity of these environments, subjects with privileged access represent a significant insider threat to the integrity of the organization's systems and data. Their position allows them to manipulate or exfiltrate sensitive information, either independently or in collaboration with external actors. The risk is further amplified as these individuals may be vulnerable to recruitment or coercion, making them potential participants in malicious activities that compromise organizational security. As insiders, their knowledge and access make them a critical point of concern for both data protection and operational security.

IF011.001Intentionally Weakening Network Security Controls For a Third Party

The subject intentionally weakens or bypasses network security controls for a third party, such as providing credentials or disabling security controls.