Detections
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- ID: DT147
- Created: 20th October 2025
- Updated: 20th October 2025
- Platforms: Windows, Linux, MacOS,
- Contributor: Ryan Bellows
Endpoint Network Access Agent Telemetry Monitoring
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.
Sections
ID | Name | Description |
---|---|---|
AF029.004 | Switching to Unmonitored Networks | The subject intentionally disconnects from monitored corporate networks (such as managed Ethernet, enterprise Wi-Fi, or secure VPN tunnels) and reconnects using alternative, unmonitored connectivity options. This may include switching to a guest Wi-Fi network, tethering through a personal mobile hotspot, or leveraging an unmanaged residential or public access point.
By exiting the boundaries of controlled infrastructure, the subject avoids endpoint-level inspection, network logging, and identity-based access enforcement. This maneuver is particularly effective in environments where endpoint telemetry is only collected while connected to corporate networks or VPN channels. In such cases, activity conducted over unmonitored networks leaves no observable trace in central logging systems, severely degrading investigative visibility.
This behavior is commonly paired with additional anti-forensics techniques (such as unauthorized VPN use, encrypted transfer protocols, or private browsing) to further frustrate detection. The deliberate choice to operate from unmonitored networks signals a clear intent to conceal operational activity and evade forensic scrutiny. |
AF029.003 | Use of Browser-Based VPN Extensions | The subject installs and activates browser-based VPN or proxy extensions (such as Hola VPN, Browsec, or ZenMate) to anonymize specific web activity while avoiding host-level detection or access restrictions. These lightweight tools require no administrative privileges and often evade traditional endpoint controls, allowing subjects to selectively obscure browsing sessions, bypass content filtering, or access external services undetected.
Unlike full-system VPN clients, browser-based VPNs operate at the application layer, making them more difficult to inventory, log, or control using conventional network or endpoint defenses. Their use complicates investigative visibility into user intent, session content, and destination domains, particularly when paired with HTTPS encryption or private browsing modes. This technique represents a form of network anti-forensics intended to obscure subject behavior with minimal system footprint or oversight. |
AF029.002 | Unauthorized VPN Usage | The subject deliberately uses Virtual Private Network (VPN) technology in a manner that circumvents organizational oversight, masking the nature, destination, or content of network activity. This includes installing unapproved VPN clients, as well as reconfiguring sanctioned VPN software to route traffic through unauthorized exit nodes, personal infrastructure, or third-party services not governed by corporate policy.
By diverting traffic away from monitored pathways, the subject obstructs standard telemetry collection - evading logging of session destinations, data transfers, or identity-bound usage. This behavior frustrates forensic reconstruction, hinders real-time monitoring, and degrades the reliability of investigative artifacts. Unauthorized VPN usage is an intentional anti-forensics measure aimed at concealing potentially harmful activity behind layers of encrypted and unsanctioned transit. |
AF029.001 | Browser or System Proxy Configuration | A subject configures either their web browser or operating system to route HTTP and HTTPS traffic through a manually defined outbound proxy server. This action enables them to redirect web activity through an external node, effectively masking the true destination of network traffic and undermining key layers of enterprise monitoring and control.
By placing a proxy between their endpoint and the internet, the subject can obscure final destinations, bypass domain-based filtering, evade SSL inspection, and suppress logging artifacts that would otherwise be available to investigative teams. This behavior, when unsanctioned, is a hallmark of anti-forensic preparation—often signaling an intent to conceal exfiltration, contact unmonitored services, or test visibility boundaries. While proxies are sometimes used for legitimate troubleshooting, research, or sandboxing purposes, their use outside approved configurations or infrastructure should be treated as an investigatory lead.
Technical MethodBoth browsers and operating systems offer mechanisms to define proxy behavior. These configurations typically involve:
Once defined, the behavior is as follows:
Proxy settings may be configured through user interfaces, system preferences, environment variables, or policy files—none of which necessarily require administrative privileges unless endpoint controls are in place.
This technique is especially potent in organizations with reliance on DNS logs, web filtering, or SSL interception as primary visibility mechanisms. It fractures investigative fidelity and should be escalated when observed in unauthorized contexts. |