Unauthorized VPN Usage

By only allowing pre-approved software to be installed and run on corporate devices, the subject is unable to install software themselves.

Disable proxy configuration changes on Windows via Group Policy. This prevents users from manually altering proxy settings in Internet Explorer/Edge and applies to system-wide proxy use (affecting Chrome and other apps that rely on WinINET settings).

Group Policy sets the following registry key:

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel] "Proxy"=dword:00000001 

This disables UI access to change proxy settings in the Internet Options panel and applies across applications using WinINET.

Policy Enforcement Notes:

• This policy applies per-user. Use loopback processing or enforce via user GPO linked to OUs if applying domain-wide.
• Chrome and Edge Chromium both honor system proxy settings unless explicitly overridden by command-line flags or extension policies.
• If managing via Intune or MDM, use the Policy CSP - Proxy or custom ADMX ingestion for equivalent enforcement.

Supported Versions:

• Windows 10 (all editions that support Group Policy, typically Pro, Enterprise, and Education)
• Windows 11 (same Group Policy-capable editions)
• Windows 8.1 / 8
• Windows 7
• Windows Server 2008 R2 through 2022 (when user policies apply)

Notes on Support:

• This setting applies only to versions that still use WinINET-based Internet Settings (i.e., Internet Explorer settings that are system-wide).
• It does not prevent proxy changes via third-party tools that bypass WinINET unless additional controls are enforced (e.g., application whitelisting, restricted registry access).
• Edge (Chromium) and Chrome will respect these proxy settings if they’re not configured independently (e.g., via extension or policy override).
• On Windows Home editions, this registry key may not take effect unless equivalent settings are configured via other methods, as Group Policy-based enforcement is not fully supported.

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.

MDM solutions require employees to register their personal devices with the organization's MDM system before gaining access to corporate networks and applications. This process ensures that only approved and known devices are permitted to connect.

Once a device is enrolled, the MDM system can enforce security policies that include:

• Access Control: Restricting or granting access based on the device's compliance with corporate security standards.
• Configuration Management: Ensuring that devices are configured securely, with up-to-date operating systems and applications.
• Remote Wipe and Lock: Allowing the organization to remotely wipe or lock a device if it is lost, stolen, or if suspicious activity is detected.
• Data Encryption: Enforcing encryption for data stored on and transmitted by the device to protect sensitive information.
• Application Control: Managing and restricting the installation of unauthorized applications that could pose security risks.

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

Next-generation firewall (NGFW) network appliances and services provide the ability to control network traffic based on rules. These firewalls provide basic firewall functionality, such as simple packet filtering based on static rules and track the state of network connections. They can also provide the ability to control network traffic based on Application Layer rules, among other advanced features to control network traffic.

A example of simple functionality would be blocking network traffic to or from a specific IP address, or all network traffic to a specific port number. An example of more advanced functionality would be blocking all network traffic that appears to be SSH or FTP traffic to any port on any IP address.

The Principle of Least Privilege should be enforced, and period reviews of permissions conducted to ensure that accounts have the minimum level of access required to complete duties as per their role.

Establish and maintain formal, well-communicated pathways for personnel to request resources, report deficiencies, or propose operational improvements. By providing structured mechanisms to meet legitimate needs, organizations reduce the likelihood that subjects will bypass policy controls through opportunistic or unauthorized actions.

Implementation Approaches

• Create clear, accessible request processes for technology needs, system enhancements, and operational support requirements.
• Ensure personnel understand how to escalate unmet needs when standard processes are insufficient, including rapid escalation pathways for operational environments.
• Maintain service-level agreements (SLAs) or expected response times to requests, ensuring perceived barriers or delays do not incentivize unofficial action.
• Integrate feedback mechanisms that allow users to suggest improvements or report resource shortfalls anonymously or through designated representatives.
• Publicize successful examples where formal channels resulted in legitimate needs being met, reinforcing the effectiveness and trustworthiness of the system.

Operational Principles

• Responsiveness: Requests must be acknowledged and processed promptly to prevent frustration and informal workarounds.
• Transparency: Personnel should be informed about request status and outcomes to maintain trust in the process.
• Accountability: Ownership for handling requests must be clearly assigned to responsible teams or individuals.
• Cultural Integration: Leaders and supervisors should reinforce the use of formal channels and discourage unsanctioned self-remediation efforts.

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.

Audit Logs are records generated by systems and applications to document activities and changes within an environment. They provide an account of events, including user actions, system modifications, and access patterns.

Implement Deep Packet Inspection (DPI) tools to inspect the content of network packets beyond the header information. DPI can identify unusual patterns and hidden data within legitimate protocols. DPI can be conducted with a range of software and hardware solutions, such as Unified Threat Management (UTM) and Next-Generation Firewalls (NGFWs), as well as Intrusion Detection and Prevention Systems (IDPS) such as Snort and Suricata, 

Logging DNS requests made by corporate devices can assist with identifying what web resources a system has attempted to or successfully accessed.

Monitor outbound DNS traffic for unusual or suspicious queries that may indicate DNS tunneling. DNS monitoring entails observing and analyzing Domain Name System (DNS) queries and responses to identify abnormal or malicious activities. This can be achieved using various security platforms and network appliances, including Network Intrusion Detection Systems (NIDS), specialized DNS services, and Security Information and Event Management (SIEM) systems that process DNS logs.

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.

Analyze network flow data (NetFlow) to identify unusual communication patterns and potential tunneling activities. Flow data offers insights into the volume, direction, and nature of traffic.

NetFlow, a protocol developed by Cisco, captures and records metadata about network flows—such as source and destination IP addresses, ports, and the amount of data transferred.

Various network appliances support NetFlow, including Next-Generation Firewalls (NGFWs), network routers and switches, and dedicated NetFlow collectors.

Monitor and analyze minor policy violations over time to detect emerging behavioral patterns that may indicate boundary testing, behavioural drift, or preparation for more serious misconduct. Isolated minor infringements may appear benign, but repeated or clustered incidents can signal a developing threat trajectory.

Detection Methods

• Maintain centralized logging of all recorded policy violations, including low-severity infractions, within case management, HR, or security systems.
• Implement analytical tools or workflows that flag individuals with multiple minor violations within defined timeframes (e.g., repeated unauthorized device use, bypassing security protocols, small unauthorized disclosures).
• Correlate minor violation data with other risk indicators such as unauthorized access attempts, changes in behavioral baselines, or indicators of disgruntlement.
• Analyze patterns across teams, units, or operational areas to detect systemic issues or cultural tolerance of rule-breaking behaviors.
• Conduct periodic behavioral risk reviews that explicitly include minor infractions as part of insider threat monitoring programs.
•  

Indicators

• Subjects accumulating multiple low-level infractions without corresponding corrective action or behavioral improvement.
• Increased frequency or severity of minor violations over time, suggesting desensitization or emboldenment.
• Violations spanning multiple domains (e.g., IT security, operational protocols, HR policy), indicating generalized disregard for rules.
• Evidence that minor violations are clustered around operational pressures, major organizational changes, or periods of reduced oversight.

Deploy User and Entity Behavior Analytics (UEBA) solutions designed for cloud environments to monitor and analyze the behavior of users, applications, network devices, servers, and other non-human resources. UEBA systems track normal behavior patterns and detect anomalies that could indicate potential insider events. For instance, they can identify when a user or entity is downloading unusually large volumes of data, accessing an excessive number of resources, or engaging in data transfers that deviate from their usual behavior.

Implement User Behavior Analytics (UBA) tools to continuously monitor and analyze user (human) activities, detecting anomalies that may signal security risks. UBA can track and flag unusual behavior, such as excessive data downloads, accessing a higher-than-usual number of resources, or large-scale transfers inconsistent with a user’s typical patterns. UBA can also provide real-time alerts when users engage in behavior that deviates from established baselines, such as accessing sensitive data during off-hours or from unfamiliar locations. By identifying such anomalies, UBA enhances the detection of insider events.

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.

Event ID 4946: A change has been made to Windows Firewall exception list. A rule was added.

This event indicates that a change has been made to the Windows Firewall settings and typically logs information about the specific settings that were changed.

Event ID 4947: A change has been made to Windows Firewall exception list. A rule was modified.

This event is logged when an outbound rule is modified in the Windows Firewall. It provides details about the rule that was changed.

Event ID 4948: A change has been made to Windows Firewall exception list. A rule was deleted.

This event is logged when an inbound rule is modified in the Windows Firewall. It provides details about the rule that was changed.

Event ID 4950: A Windows Firewall setting has changed.

This event indicates that a change has been made to the Windows Firewall's global configuration, such as enabling or disabling the firewall.