What the heck is X11 Forwarding??

X11 forwarding is a mechanism that allows a user to start up remote applications, and then forward the application display to their local Windows machine.

X11Forwarding

For this to work, we have to allow X11 forwarding in the SSH configuration file (/etc/ssh/sshd_config) on the server that provides the application by changing this option to yes..

Usage

With this we can start the application from our client with the following command:

X11 Security

X11 is insecure without appropriate measures, as it communicates unencrypted. An open X server can expose window contents to anyone on the network, allowing tools like xwd and xgrabsc to capture keystrokes, screenshots, and control the mouse remotely.

Exploited XServer Vulnerabilities

Vulnerabilities in XServer have been exploited to execute arbitrary code with user privileges on UNIX and Linux systems, including Red Hat Enterprise Linux, Ubuntu, and SUSE Linux. Notable vulnerabilities include CVE-2017-2624, CVE-2017-2625, and CVE-2017-2626.