Hunting and Exploiting Vulnerable Windows Drivers

Introduction

When it comes to privilege escalation on Windows systems, vulnerable kernel-mode drivers are a gold mine for attackers. These drivers, often loaded with administrative privileges, can be abused to read/write kernel memory, escalate privileges, or even bypass security tools.

This post will walk you through how to find vulnerable drivers, analyze them, and exploit them — all within a controlled and ethical lab environment.

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What Makes Drivers Dangerous?

Windows kernel drivers operate with high-level privileges. When poorly written drivers expose dangerous IOCTL handlers or allow arbitrary memory access, they become perfect targets for attackers.

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Part 1: Finding Vulnerable Drivers on a Windows System

Step 1: Enumerate Installed Drivers

Use PowerShell or built-in tools to list installed and loaded drivers:

Get-WmiObject Win32_SystemDriver | Select-Object Name, PathName, StartMode, State

Or via CMD:

driverquery /V /FO CSV > drivers.csv

Step 2: Identify Known Vulnerable Drivers

Once you have the list:

• Extract the driver name and version

• Cross-reference them on:

  • https://www.cvedetails.com/

  • https://www.exploit-db.com/

  • https://github.com/SecWiki/windows-kernel-exploits

Automation Tip: Use tools like:

• WinDriverView

• Custom PowerShell scripts

• GitHub tools like VulnDriverScanner

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Part 2: Downgrading to a Vulnerable Driver

Often, you’ll need to forcefully install an old driver version that’s known to be vulnerable.

Preparation (Lab Only!)

• Use a VM (VirtualBox/VMware)

• Disable Driver Signature Enforcement:

bcdedit /set testsigning on
bcdedit /set nointegritychecks on

Reboot after making the change.

Also disable HVCI/Memory Integrity from Windows Security > Core Isolation.

Step-by-Step Downgrade Process

1. Remove the Existing Driver

pnputil /delete-driver oemXX.inf /uninstall /force

Or via Device Manager: Uninstall and check "Delete driver software".

2. Install Vulnerable Version

Use a loader like:

• OSR Driver Loader

• Manual install via SC:

sc create vulnDrv binPath= C:\path\vuln.sys type= kernel start= demand
sc start vulnDrv

Or map it manually using tools like kdmapper.

3. Verify It's Loaded

Get-WmiObject Win32_SystemDriver | Where-Object { $_.Name -eq "vulnDrv" }

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Part 3: Analyzing and Exploiting the Driver

Step 1: Identify IOCTL Codes

Use tools like:

• Process Monitor

• WinObj

• ioctl-fuzzer

Look for unprotected or poorly validated DeviceIoControl() calls.

Step 2: Write Exploit

Use DeviceIoControl() in C/C++ or Python to send malicious IOCTLs.

A basic C++ snippet:

HANDLE hDevice = CreateFile(L"\\\\.\\VulnDevice", ...);
DWORD bytesReturned;
DeviceIoControl(hDevice, IOCTL_VULN_CODE, inBuf, inSize, outBuf, outSize, &bytesReturned, NULL);

Real Exploits Examples

Driver	CVE	Exploit
Capcom.sys	CVE-2016-1531	https://github.com/KaLendsi/CVE-2016-1531
RTCore64.sys (MSI)	CVE-2019-16098	Kernel R/W, LPE
HackSysExtremeVulnerableDriver	-	Training driver with multiple PoCs

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Cleanup

When you're done:

sc stop vulnDrv
sc delete vulnDrv
bcdedit /set testsigning off
bcdedit /set nointegritychecks off

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Pro Tips for Red Teamers

• Always use VMs with snapshots

• Use WinDbg, Ghidra, or IDA Pro to reverse IOCTL handlers

• Automate exploit testing via custom fuzzers

• Load unsigned drivers via kdmapper

• Document everything — from IOCTL codes to crash behavior

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Further Reading

• SecWiki Windows Kernel Exploits
• HackSys Extreme Vulnerable Driver
• Windows Internals - Microsoft
• Capcom.sys Local PrivEsc

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Conclusion

Vulnerable drivers are a powerful, often overlooked attack surface. When properly understood, they provide deep insights into Windows internals and real-world privilege escalation scenarios. Mastering them will up your game in red teaming, CTFs, and exploit dev.

Stay safe. Test smart. Hack ethically.

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REFERENCES

• https://github.com/FourCoreLabs/LolDriverScan