Notes

Do not su from untrusted accounts

It is common practice not to be "too concerned" about one's personal accounts on a system and to regularly su to root (or other trusted accounts such as http) from it. This is based on a belief that during the su, running as root you are insulated from any problems with the ordinary account.

Unfortunately, you are sharing a terminal (tty) device with the untrusted user and various environment variables such as $DISPLAY. This allows a cracker to use the compromised ordinary account to sniff passwords by reading from the tty device, hijack "trusted" X11 sessions using an altered $DISPLAY environment variable, etc.

This is a serious vulnerability. Also, it is a good reason, when allowing system administrators to SSH into important systems, to allow them to SSH directly to root rather than forcing them to SSH into ordinary accounts and then su to root. Certainly, a very strong root password is required and monitoring for crackers guessing it is required too.

Another laptop with valuable data stolen

In September of 2000, a laptop that was believed to contain confidential company information belonging to Qualcomm Chairman Irwin Jacobs was stolen at a conference. If he had followed the advice in the book then his only loss would have been the hardware, not potentially millions of dollars that disclosure of its data might cause.

Koules1.4 game program has root vulnerability

Koules1.4, a game program, is vulnerable to stack smashing. Since it runs set-UID to root, it should be removed from the system.

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