RDP Hijacking

Adversaries may hijack a legitimate user's remote desktop session to move laterally within environment. Remote desktop is a common feature in operating systems. It allows a user to log into an interactive session with a system desktop graphical user interface on a remote system. Microsoft refers to its implementation of the Remote Desktop Protocol (RDP) as Remote Desktop Services (RDS).

Adversaries may perform RDP session hijacking which involves stealing a legitimate user's remote session. Typically, a user is notified when someone else is trying to steal their session. With System permissions and using Terminal Services Console. C:\Windows\System32\tscon.exe [session number to be stolen], an adversary can hijack a session without the need for credentials or prompts to the user. This can be done remotely or locally and with active or disconnected session. It can also lead Remote System Discovery and Privilege Escalation by stealing a Domain Admin or higher privileged account session. All of this can be done by using native Windows commands, but it has also been added as a feature in red teaming tools.

Example

It is possible to switch from one user's desktop to another through the use of tscon, this will require us to have

NT AUTHORITY/SYSTEM

Will first query users to check for any active sessions

Then we use the tscon utility to switch sessions that are currently available

And we manage to access another session

RDP-Hijacking Demo: