Switching to Unmonitored Networks

Deploy and enforce the use of Endpoint Network Access Agents (such as Zscaler Client Connector, Cisco AnyConnect Secure Mobility Client, or similar tools) to ensure continuous network policy enforcement, traffic inspection, and behavioral visibility across all user environments, including remote, hybrid, and guest networks.

Key Prevention Measures:

• Mandatory Agent Deployment: Require persistent agent installation across all managed endpoints, using device posture checks to validate status and prevent circumvention.
• Controlled Network Access: Prevent outbound traffic unless routed through approved inspection points—eliminating unmonitored internet connectivity and forcing adherence to network governance policies.
• VPN Configuration Lockdown: Restrict VPN usage to sanctioned clients and configurations. Enforce full-tunnel routing, disable split-tunneling, and block execution of unauthorized VPN applications or browser-based VPN extensions.
• Policy-Based Access Control: Apply conditional access rules based on endpoint compliance, user identity, and network context—ensuring secure posture is maintained regardless of location.
• Tamper Protection and Lockout: Detect and respond to agent disablement, configuration drift, or telemetry loss through auto-remediation or access revocation mechanisms.
• Cross-Network Consistency: Extend enforcement capabilities to unmanaged and public networks, reducing blind spots introduced by subjects switching to guest Wi-Fi, personal hotspots, or external connectivity paths.

This control directly mitigates multiple behaviors associated with Network Obfuscation, including the use of unauthorized VPNs, evasive browser extensions, and transitions to unmonitored networks.

Commercial security software may include native anti-tampering protections that prevent attempts to interfere with its operations, such as deleting or renaming required files.

This section cannot be readily mitigated at a system level with preventive controls since it is based on the abuse of fundamental features of the system.

An agent capable of Endpoint Detection and Response (EDR) is a software agent installed on organization endpoints (such as laptops and servers) that (at a minimum) records the Operating System, application, and network activity on an endpoint.

Typically EDR operates in an agent/server model, where agents automatically send logs to a server, where the server correlates those logs based on a rule set. This rule set is then used to surface potential security-related events, that can then be analyzed.

An EDR agent typically also has some form of remote shell capability, where a user of the EDR platform can gain a remote shell session on a target endpoint, for incident response purposes. An EDR agent will typically have the ability to remotely isolate an endpoint, where all network activity is blocked on the target endpoint (other than the network activity required for the EDR platform to operate).

An agent capable of User Activity Monitoring (UAM) is a software agent installed on organization endpoints (such as laptops); typically, User Activity Monitoring agents are only deployed on endpoints where a human user Is expected to conduct the activity.

The User Activity Monitoring agent will typically record Operating System, application, and network activity occurring on an endpoint, with a focus on activity that is or can be conducted by a human user. The purpose of this monitoring is to identify undesirable and/or malicious activity being conducted by a human user (in this context, an Insider Threat).

Typical User Activity Monitoring platforms operate in an agent/server model where activity logs are sent to a server for automatic correlation against a rule set. This rule set is used to surface activity that may represent Insider Threat related activity such as capturing screenshots, copying data, compressing files or installing risky software.

Other platforms providing related functionality are frequently referred to as User Behaviour Analytics (UBA) platforms.

An agent capable of User Behaviour Analytics (UBA) is a software agent installed on organizational endpoints (such as laptops). Typically, User Activity Monitoring agents are only deployed on endpoints where a human user is expected to conduct the activity.

The User Behaviour Analytics agent will typically record Operating System, application, and network activity occurring on an endpoint, focusing on activity that is or can be conducted by a human user. Typically, User Behaviour Analytics platforms operate in an agent/server model where activity logs are sent to a server for automatic analysis. In the case of User Behaviour Analytics, this analysis will typically be conducted against a baseline that has previously been established.

A User Behaviour Analytic platform will typically conduct a period of ‘baselining’ when the platform is first installed. This baselining period establishes the normal behavior parameters for an organization’s users, which are used to train a Machine Learning (ML) model. This ML model can then be later used to automatically identify activity that is predicted to be an anomaly, which is hoped to surface user behavior that is undesirable, risky, or malicious.

Other platforms providing related functionality are frequently referred to as User Activity Monitoring (UAM) platforms.

Leverage telemetry produced by Endpoint Network Access Agents (such as Zscaler Client Connector or Cisco AnyConnect Secure Mobility Client) to detect network-layer evasion attempts, obfuscation behaviors, or deviations from expected usage patterns in hybrid and remote environments.

Detection Methods:

• Per-Session Telemetry Analysis: Collect detailed logs of outbound destination IPs, domain names, protocols, and session metadata from the agent. Correlate with identity logs to validate that the subject's traffic aligns with role-based expectations.
• Geographic and Network Mismatch: Detect inconsistencies between subject geolocation (from agent logs) and declared work location, or anomalous IPs (e.g., Tor exit nodes, commercial VPN infrastructure) accessed during active sessions.
• Split-Tunnel Indicators: Analyze whether only partial traffic is visible in agent logs. Absence of common destinations (e.g., productivity platforms, update services) may indicate concurrent use of a secondary tunnel outside agent visibility.
• Extension-Specific Access Patterns: Identify repeated access to known VPN browser extensions or proxy service endpoints from within the inspected agent traffic, suggesting circumvention efforts within the tunnel.
• Traffic Timing Correlation: Compare network activity timestamps from the agent with endpoint activity logs (e.g., EDR or system audit logs). Large gaps may indicate periods of disconnection, traffic redirection, or uninspected activity.
• Policy Bypass Attempts: Monitor for failed or repeated attempts to reach restricted domains, use unauthorized ports, or alter routing behavior as captured in agent logs. These may indicate probing or manipulation of enforcement boundaries.

This detection approach assumes full deployment and telemetry integration of the access agent, enabling fine-grained monitoring of network obfuscation behaviors even in decentralized, off-corporate-network scenarios.

Custom or pre-built detection logic can be used to determine if a user account has authenticated from two geographic locations in a period of time that is not feasible for legitimate travel between the locations.

Depending on the type of VPN appliance or service used, VPN logs can provide detailed records of user activity. These logs typically include information such as user IDs, device types, IP addresses, and connection timestamps. By analyzing VPN logs, security teams can identify deviations from normal usage patterns, such as connections from unusual geographic locations, access during odd hours, or unusually large data transfers. Anomalies in VPN usage can serve as early indicators of suspicious behavior, potentially signaling attempts at data exfiltration or other unauthorized activities. Alerts triggered by these irregularities allow for further investigation to assess potential threats.