Defeating VPN Always-On
10-18, 10:00–10:30 (Europe/Luxembourg), Salle Europe

VPN Always-On is a security control that can be deployed to mobile endpoints that remotely access corporate resources through VPN. It is designed to prevent data leaks and narrow attack surface of enrolled end-user equipment connected to untrusted networks. When it is enforced, the mobile device can only reach the VPN gateway and all connections are tunnelled.

We will review the relevant Windows API, the practicalities of this feature, look at popular VPN software ; we will then consider ridiculously complex exfil methods and... finally bypass it with unexpectedly trivial tricks. We will exploit design, implementation and configuration issues to circumvent this control in offensive scenarios. We will then learn how to fix or harden VPN Always-On deployment to further limit the risks posed by untrusted networks.

This talk is more than just the outcome of my technical research against one particular network security feature. It is an attempt to fully embrace the hacker spirit through the revolt against Control, the unreasonable time trying to understand the technological subtleties and finally the sharing of beautifully simple techniques to break free.

Maxime Clementz is a Senior Manager within the Cybersecurity Advisory team of PwC Luxembourg. He develops his ethical hacker skills by committing himself to various assignments for big companies, banks and European institutions. As a technical specialist, he leads penetration tests, red-teaming, digital forensics and incident response missions.
He contributes to the development of the team’s hacking capabilities by sharing the results of his technology watch and R&D and is now leading the CSIRT and Threat Intelligence initiatives of PwC Luxembourg. He especially enjoys sharing knowledge by presenting the results of each mission or by giving talks (Hack.lu 2012, 2015, 2017) and training courses. Maxime teaches IT security at a French engineering school and organizes a Capture the Flag event for the students.