Detecting and Preventing Hyper-V, Virtual NIC, and RDP Takeover Persistence on Windows Servers – A Complete Incident Response & Hardening Guide

Modern Windows Server attacks rarely stop at initial access. Once attackers obtain administrator or SYSTEM-level execution, they often attempt to establish persistence by enabling Hyper-V, creating virtual machines, virtual switches, or virtual network adapters (vNICs). This allows them to:

• Hide malicious workloads inside virtual machines

• Bypass traditional security monitoring

• Hijack or proxy Remote Desktop Services (RDP)

• Maintain long-term covert access

In your case, multiple high-risk blocked executions were detected and prevented by CatchPulse, indicating an attempted post-exploitation phase.
This article documents the problem, analysis, validation process, prevention strategy, and final automated scripts, written in a SOC / audit-ready format.

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Problem Statement

Security logs showed repeated blocking of:

• Credential dumping tools

• RDP-related utilities

• Administrator-level PowerShell abuse

• Execution attempts from temporary directories

Such behavior commonly precedes attempts to:

• Enable Hyper-V silently

• Create vEthernet adapters / virtual switches

• Deploy hidden virtual servers or routers

• Persist across reboots using boot-level hypervisor settings

Even though these attempts were blocked, it was critical to validate that no persistence already existed and to ensure future protection.

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Risk Overview

If Hyper-V or virtualization persistence is successfully established, attackers can:

• Operate malware outside the host OS visibility

• Intercept or redirect RDP traffic

• Create rogue internal networks

• Evade antivirus and EDR tools

• Maintain stealth access even after password resets

Therefore, verification + continuous monitoring is mandatory after such alerts.

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Solution Overview

The solution is implemented in three controlled phases:

1. Validation – Confirm no Hyper-V / vNIC persistence exists

2. Automation – Run all checks using a single audit script

3. Prevention & Alerting – Detect and alert if Hyper-V is ever enabled again

All scripts are read-only by default, evidence-friendly, and safe for production servers.

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Phase 1 – Validation Strategy (What We Check)

The audit validates all known persistence vectors:

• Hyper-V Windows Features

• Hypervisor boot configuration

• Virtual machines

• Virtual switches

• Virtual network adapters (vNICs)

• Hyper-V services

• File system artifacts

• Registry virtualization keys

• Scheduled tasks

If any single check fails, it indicates prior or active persistence.

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Phase 2 – Automatic Audit Script

Hyper-V / vNIC Persistence Audit (Read-Only)

Purpose

• One-click validation

• Generates timestamped evidence logs

• No system changes

Script: HyperV_Persistence_Audit.ps1

# ===============================
# Hyper-V Persistence Audit Script
# Read-only | Evidence-ready
# ===============================

$LogFile = "C:\SecurityAudit\HyperV_Audit_$(Get-Date -Format yyyyMMdd_HHmmss).log"
New-Item -ItemType Directory -Path C:\SecurityAudit -Force | Out-Null

function Log($msg) {
    $msg | Tee-Object -FilePath $LogFile -Append
}

Log "===== Hyper-V Persistence Audit Started ====="
Log "Date: $(Get-Date)"
Log "Hostname: $env:COMPUTERNAME"
Log "--------------------------------------------"

# 1. Hyper-V Feature Check
Log "`n[1] Hyper-V Windows Features:"
Get-WindowsOptionalFeature -Online |
Where-Object FeatureName -like "*Hyper*" |
ForEach-Object { Log "$($_.FeatureName) : $($_.State)" }

# 2. Hypervisor Boot Persistence
Log "`n[2] Hypervisor Boot Configuration:"
bcdedit | findstr hypervisor | ForEach-Object { Log $_ }

# 3. Hyper-V Services
Log "`n[3] Hyper-V Services:"
Get-Service | Where-Object Name -match "vmms|vmcompute|vmic" |
ForEach-Object { Log "$($_.Name) - $($_.Status)" }

# 4. Virtual Machines
Log "`n[4] Virtual Machines:"
try { Get-VM | ForEach-Object { Log $_.Name } }
catch { Log "Hyper-V module not present" }

# 5. Virtual Switches
Log "`n[5] Virtual Switches:"
try { Get-VMSwitch | ForEach-Object { Log $_.Name } }
catch { Log "No virtual switches found" }

# 6. Network Adapters
Log "`n[6] Network Adapters:"
Get-NetAdapter | ForEach-Object {
    Log "$($_.Name) | $($_.InterfaceDescription)"
}

# 7. Hyper-V File Artifacts
Log "`n[7] Hyper-V File Artifacts:"
@(
    "C:\Program Files\Hyper-V",
    "C:\ProgramData\Microsoft\Windows\Hyper-V"
) | ForEach-Object {
    Log "$_ : $(Test-Path $_)"
}

# 8. Registry Virtualization Key
Log "`n[8] Registry Check:"
try {
    reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Virtualization" |
    ForEach-Object { Log $_ }
} catch {
    Log "Registry key not found"
}

# 9. Scheduled Tasks
Log "`n[9] Scheduled Tasks:"
Get-ScheduledTask |
Where-Object TaskName -match "Hyper|VM|vSwitch|vEthernet" |
ForEach-Object { Log $_.TaskName }

Log "`n===== Audit Completed ====="
Log "Log saved to: $LogFile"

How It Works

• Collects system state

• Writes immutable logs

• Confirms absence or presence of virtualization artifacts

Expected Safe Result

• Hyper-V features Disabled

• No VMs, no vSwitches

• No vEthernet adapters

• Hypervisor launch Off

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Phase 3 – Continuous Alerting (Prevention)

Even after validation, future enablement must be detected immediately.

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Hyper-V Guard Script (Continuous Monitoring)

Purpose

• Detects Hyper-V enablement

• Detects boot-level hypervisor activation

• Generates alerts automatically

Script: HyperV_Guard.ps1

$AlertLog = "C:\SecurityAudit\HyperV_ALERT.log"

$HyperVEnabled = Get-WindowsOptionalFeature -Online |
Where-Object FeatureName -like "*Hyper*" |
Where-Object State -eq "Enabled"

$HypervisorBoot = (bcdedit | findstr hypervisor) -match "Auto"

if ($HyperVEnabled -or $HypervisorBoot) {

    $msg = @"
ALERT: Hyper-V ENABLED
Date: $(Get-Date)
Hostname: $env:COMPUTERNAME
Feature Enabled: $($HyperVEnabled.FeatureName)
Boot Hypervisor: $HypervisorBoot
"@

    $msg | Tee-Object -FilePath $AlertLog -Append

    Write-EventLog -LogName Application `
        -Source "HyperV-Guard" `
        -EventId 9001 `
        -EntryType Error `
        -Message $msg
}

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Scheduling the Guard (Automatic)

schtasks /create /sc minute /mo 15 /tn "HyperV_Guard" `
/tr "powershell.exe -ExecutionPolicy Bypass -File C:\SecurityAudit\HyperV_Guard.ps1" `
/ru SYSTEM

What This Achieves

• Runs every 15 minutes

• No user interaction required

• Immediate detection of misuse

• Event Viewer + log file alerts

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Best Practices & Hardening Recommendations

• Disable daily use of built-in Administrator

• Restrict PowerShell to AllSigned

• Block dism.exe and bcdedit.exe for non-admins

• Restrict RDP by country IP

• Review virtualization status after every security alert

• Retain audit logs for compliance

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Conclusion

This approach ensures that:

• No Hyper-V, virtual NIC, or virtual router persistence exists

• Any future attempt is detected immediately

• Security posture remains defensive, verifiable, and auditable

Most importantly, it converts a security incident into a controlled, monitored, and hardened environment.

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