Hidden Users

Adversaries may use hidden users to hide the presence of user accounts they create or modify. Administrators may want to hide users when there are many user accounts on a given system or if they want to hide their administrative management accounts from other users.\

On Linux Systems, adversaries may hide user accounts from the login screen, also referred to as the greeter. The method an adversary may user depends on which Display Manager the distribution is currently using. For example, on an Ubuntu using the GNOME Display Manager(GDM), accounts may be hidden from the greeter using the gsettings command(ex: sudo -u gdm gsettings set org.gnome.login-screeen disable-user-list true). Display Managers are not anchored to specific distributions and may be changed by a user or adversary.

Now check the user login screen to see the multiple users available on the system