GetOSVersion.h

#pragma once

#include <Windows.h>

// Ref: https://www.geoffchappell.com/studies/windows/km/ntoskrnl/structs/kuser_shared_data/index.htm
#define KUSER_SHARED_DATA 0x7ffe0000
#define MAJOR_VERSION_OFFSET 0x026C
#define MINOR_VERSION_OFFSET 0x0270
#define BUILD_NUMBER_OFFSET 0x0260

void get_os_version() {
	PULONG pMajorVersion = (PULONG)(KUSER_SHARED_DATA + MAJOR_VERSION_OFFSET);
	PULONG pMinorVersion = (PULONG)(KUSER_SHARED_DATA + MINOR_VERSION_OFFSET);
	PULONG pBuildNumber = (PULONG)(KUSER_SHARED_DATA + BUILD_NUMBER_OFFSET);

	// Get values using pointer deferencing
	ULONG majorVersion = (*pMajorVersion);
	ULONG minorVersion = (*pMinorVersion); 
	ULONG buildNumber = (*pBuildNumber);

	// [DEBUG]
	printf("[+] OS Major Version: %d\n", majorVersion);
	printf("[+] OS Minor Version: %d\n", minorVersion);
	printf("[+] OS Build Number: %d\n", buildNumber);

	// Determine OS Version using above-mentioned values
	if (majorVersion == 10 && minorVersion == 0) {
		printf("[+] Windows 10 / Server 2016\n");
	}
	else if (majorVersion == 6 && minorVersion == 1 && buildNumber == 7601) {
		printf("[+] Windows 7 SP1 / Server 2008 R2\n");
	}
	else if (majorVersion == 6 && minorVersion == 2) {
		printf("[+] Windows 8 / Server 2012\n");
	}
	else if (majorVersion == 6 && minorVersion == 3) {
		printf("[+] Windows 8.1 / Server 2012 R2\n");
	}
	else {
		printf("[-] Unsupported!\n");
	}
}