Bugtraq,

I (Josh Berry) discovered an authenticated command injection vulnerability
in the Demo PowerShell notification script provided by versions of PRTG
Network Monitor prior to 18.2.39.  The PowerShell notifications demo script
on versions of the application prior to 18.2.39 do not properly sanitize
input in the Parameter field.  The web application provides a security
control around running executables/scripts as part of a notification, but
the demo PowerShell script contains a command injection vulnerability.  As a
proof of concept, the following value can be passed in the Parameter
field, resulting in the creation of a test account named pentest:

              Test.txt;net user pentest p3nT3st! /add

This bypasses the security control in place for the application.  I notified
Paessler AG, the developer of the application, and they have since patched
the issue and assigned a CVE of CVE-2018-9276.  Additional details are
provided below:

# Vulnerability Title: PRTG < 18.2.39 Command Injection Vulnerability
# Google Dork: N/A, but more details at:
https://www.codewatch.org/blog/?p=453 
# Date: Initial report: 2/14/2018, disclosed on 6/25/2018
# Exploit Author: Josh Berry
# Vendor Homepage: https://www.paessler.com  
# Software Link: https://www.paessler.com/download/prtg-download?download=1 
# Vulnerable Version Tested: 18.1.37.12158
# Patched Version: 18.2.39
# Tested on: Windows 7 and Windows Server 2012 R2
# CVE : CVE-2018-9276

Outside of patching, a workaround would be to just remove the PowerShell
demo script from the notifications directory found in the documentation:
https://www.paessler.com/manuals/prtg/notifications_settings#program. 

Note that exploiting this issue requires authenticated access.  The tool
installs with the default credentials of prtgadmin / prtgadmin
(https://kb.paessler.com/en/topic/433-what-s-the-login-name-and-password-for
-the-prtg-web-interface-and-enterprise-console-how-to-change), and it is
common for organizations to leave defaults in place or take time in changing
them based on my penetration testing experience. 

Thanks,

Josh Berry, OSCP & GCIA Gold
Project Lead - CodeWatch

Cell 469.831.8543 | josh.berry@codewatch.org | www.codewatch.org