Credits

Before I begin, those who helped me create this project shall be credited.

• Can1357, for helping me find the correct page in physical memory.
• buck, for teaching me everything about paging tables. (although not used in this project)
• Ch40zz, for helping me fix many issues in things I could never have fixed.
• wlan, I used your drv_image class :)

Physmeme

Given ANY map/unmap (read/write) of physical memory, one can now systematically map unsigned code into ones kernel. Many drivers expose this primitive and now can all be exploited by simply coding a few functions.

What versions of windows does this mapper support?

This mapper should work without any issues for pretty much all versions of relevant windows. Tested on windows 10 (1803-1909), but should support all the way back to vista.

What drivers support physical read/write?

Any driver exposing MmMapIoSpace/MmUnmapIoSpace or ZwMapViewOfSection/ZwUnmapViewOfSection can be exploited. This means bios flashing utils, fan speed utils (like MSI Afterburner), or general windows system utilities that expose physical read/write.

If you are in any sort of doubt about the abundance of these drivers simply go to this page and ctrl-f "MmMapIoSpace". (24 results)

How does this exploit work?

Since we are able to read/write to any physical memory on the system the goal is to find the physical page of a syscall and map it into our process. This can be done by calculating the offset into the page in which the syscall resides. Doing so is trivial and only requires the modulus operation.

auto syscall_page_offet = rva % 0x1000;

Now that we know that the syscalls bytes are going to be that far into the physical page we can map each physical page into our process 512 at a time (2mb) and then check the page + page_offset and compare with the syscalls bytes. After we have the syscalls page mapped into our process we can pretty much call any function inside of the kernel simply by installing an inline hook into that mapped page and then calling into the syscall.

How long does it take to find the physical page?

Less then one second. For each physical memory range I create a thread that maps 2mb at a time of physical memory and scans each physical page. This is on a system with 16gb.

In other words... its very fast, you wont need to worry about waiting to find the correct page.

How to use

There are four functions that need to be altered to make this mapper work for you. I will cover each one by one. These functions are defined inside of a physmeme.hpp and need to stay inside of this file. This allows people to make different physmeme.hpp files for each driver they want to abuse. Modular code.

When writing your driver you will need a custom entry point just like every other driver mapper.

HANDLE load_drv()

Load driver must take zero parameters and return a handle to the driver. Here is an example of this:

/*
	please code this function depending on your method of physical read/write.
*/
HANDLE load_drv()
{
	static const auto load_driver_ptr = 
		reinterpret_cast<__int64(*)()>(
			GetProcAddress(LoadLibrary("pmdll64.dll"), "LoadPhyMemDriver"));

	if (load_driver_ptr)
		load_driver_ptr();

	//--- i dont ever use this handle, its just an example of what you should do.
	return CreateFileA("\\\\.\\PhyMem", 0xC0000000, 3u, 0i64, 3u, 0x80u, 0i64);
}

note: my exploited driver actually came with a dll that exported all the functions.

bool unload_drv()

Unload driver can and should return a bool but its not needed. There is also no need to pass any paremeters since the driver handle is global.

/*
	please code this function depending on your method of physical read/write.
*/
bool unload_drv()
{
	static const auto unload_driver_ptr = 
		reinterpret_cast<__int64(*)()>(
			GetProcAddress(LoadLibrary("pmdll64.dll"), "UnloadPhyMemDriver"));
	return unload_driver_ptr ? unload_driver_ptr() : false;
}

std::uintptr_t map_phys(std::uintptr_t addr, std::size_t size)

This function MUST take two parameters the first is the physical address to be mapped, the second is the size to be mapped. The return value is the virtual address of the mapping.

/*
	please code this function depending on your method of physical read/write.
*/
std::uintptr_t map_phys(
	std::uintptr_t addr,
	std::size_t size
)
{
	//--- ensure the validity of the address we are going to try and map
	if (!is_valid(addr))
		return NULL;

	static const auto map_phys_ptr = 
		reinterpret_cast<__int64(__fastcall*)(__int64, unsigned)>(
			GetProcAddress(LoadLibrary("pmdll64.dll"), "MapPhyMem"));
	return map_phys_ptr ? map_phys_ptr(addr, size) : false;
}

bool unmap_phys(std::uintptr_t addr, std::size_t size)

This function must take the virtual address of the mapping (the address returned from map_phys) and the size that was mapped. If this function is unable to free the memory you will blue screen because you will run out of ram (happend a few times to me).

/*
	please code this function depending on your method of physical read/write.
*/
bool unmap_phys(
	std::uintptr_t addr,
	std::size_t size
) 
{
	static const auto unmap_phys_ptr = 
		reinterpret_cast<__int64(*)(__int64, unsigned)>(
			GetProcAddress(LoadLibrary("pmdll64.dll"), "UnmapPhyMem"));
	return unmap_phys_ptr ? unmap_phys_ptr(addr, size) : false;
}

DriverEntry

you can change the paremeters you pass to driver entry simply by changing this:

using DRIVER_INITIALIZE = NTSTATUS(__stdcall*)(std::uintptr_t, std::size_t);

right now your entry point should look like this:

NTSTATUS DriverEntry(PVOID lpBaseAddress, DWORD32 dwSize)

The source the hello-world.sys is the following:

#include <ntifs.h>

NTSTATUS DriverEntry(PVOID lpBaseAddress, DWORD32 dwSize)
{
	DbgPrint("> Base Address: 0x%p, Size: 0x%x", lpBaseAddress, dwSize);
	return STATUS_SUCCESS;
}

System Crash Probability

I made a small test to see the average amount of times you could hook NtTraceControl and call into it before having another thread call into it at the same time or patch guard detecting you have patched code in ntoskrnl. Here are the results:

• 6,004 calls
• 2,194 calls
• 6,897 calls
• 679 calls
• 17,159 calls
• 4,140 calls

6004 + 2194 + 6897 +679 + 17159 + 4140 = 37073 37073 / 6 = 6178.83333333

On average one in every 6,178 syscalls will another thread call into the function that is currently hooked. It takes three syscalls to map a driver if you are clearing the pe header.

6,178 / 3 = 2059

So on average one in every 2,059 drivers mapped you will crash once.

2059 / 3 = 686

If you were to use physmeme to load your driver three times a day it would take on average 686 days to crash your system.