EDR Evasion Techniques and How Sysmon Can Detect Them

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Endpoint Detection and Response (EDR) evasion techniques are advancing rapidly, but strategic Sysmon configurations can help detect what EDRs miss. Attackers bypass endpoint security using:

  • Kernel hooking/unhooking – Monitor `Process Access (Event ID 10)` for suspicious handle permissions.
  • Direct syscall injections – Track unusual thread creation (Event ID 8) in sensitive processes.
  • DLL unhooking – Analyze DLL loading patterns (Event ID 7) and correlate with thread injections.
  • Process hollowing – Validate parent-child relationships (Event ID 1) and unusual memory writes.
  • APC injection – Implement filtering for remote thread creation in targeted applications.

Deploying Sysmon alongside EDR creates a layered defense with visibility into kernel-level and memory manipulation techniques that traditional solutions often miss.

🔗 Reference: Leveraging Sysmon to Complement EDR and Address Evasion Techniques

You Should Know:

Detecting Kernel Hooking/Unhooking

  • Sysmon Configuration: 
    <RuleGroup name="Process Access Monitoring" groupRelation="or">
<ProcessAccess onmatch="include">
<TargetImage condition="contains">lsass.exe</TargetImage>
<GrantedAccess condition="is">0x1FFFFF</GrantedAccess>
</ProcessAccess>
</RuleGroup>
  • Linux Alternative (Auditd): 
    sudo auditctl -a always,exit -F arch=b64 -S ptrace -k process_access_monitoring

Detecting Direct Syscall Injections

  • Sysmon Event ID 8 (CreateRemoteThread): 
    <RuleGroup name="Suspicious Thread Creation" groupRelation="or">
<CreateRemoteThread onmatch="include">
<StartModule condition="contains">C:\Windows\System32\kernel32.dll</StartModule>
</CreateRemoteThread>
</RuleGroup>
  • Windows Command (Detect Remote Threads): 
    Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-Sysmon/Operational'; ID=8} | Where-Object { $<em>.Properties[bash].Value -ne $</em>.Properties[bash].Value }

Detecting DLL Unhooking

  • Sysmon Event ID 7 (Image Loaded): 
    <RuleGroup name="DLL Monitoring" groupRelation="or">
<ImageLoad onmatch="include">
<ImageLoaded condition="contains">C:\Temp\</ImageLoaded>
</ImageLoad>
</RuleGroup>
  • Linux (Detect LD_PRELOAD Hijacking): 
    sudo grep -r LD_PRELOAD /etc/environment /proc//environ

Detecting Process Hollowing

  • Sysmon Event ID 1 (Process Creation): 
    <RuleGroup name="Suspicious Parent-Child" groupRelation="or">
<ProcessCreate onmatch="include">
<ParentImage condition="contains">C:\Windows\System32\cmd.exe</ParentImage>
<Image condition="contains">C:\Windows\System32\notepad.exe</Image>
</ProcessCreate>
</RuleGroup>
  • Windows Command (Check Hollowed Processes): 
    Get-Process | Where-Object { $<em>.Modules | Where-Object { $</em>.FileName -notlike "C:\Windows\" } }

Detecting APC Injection

  • Sysmon Configuration: 
    <RuleGroup name="APC Injection Detection" groupRelation="or">
<CreateRemoteThread onmatch="include">
<StartAddress condition="end with">0x00007FF</StartAddress>
</CreateRemoteThread>
</RuleGroup>
  • Windows (List APC Queues): 
    Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-Sysmon/Operational'; ID=8} | Where-Object { $_.Properties[bash].Value -match "APC" }

What Undercode Say:

EDR evasion is a persistent challenge, but combining Sysmon with EDR provides deeper visibility into malicious activities. Properly configured Sysmon rules can detect stealthy techniques like direct syscalls, process hollowing, and APC injection. Log volume remains a concern, but selective filtering and SIEM integration can help manage it.

Expected Output:

  • Sysmon logs flagging suspicious process access (Event ID 10).
  • Alerts on unusual remote thread creation (Event ID 8).
  • Detection of anomalous DLL loading (Event ID 7).
  • Identification of mismatched parent-child processes (Event ID 1).
  • Logs highlighting APC injection attempts.

Prediction:

As attackers refine evasion techniques, defenders will increasingly rely on multi-layered logging (Sysmon + EDR + Auditd) to detect advanced threats. AI-driven log analysis will become essential to manage the growing volume of security events.

References:

Reported By: Patrick Bareiss – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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