Re: Escape sequences (was Wall and talkd pass binary data)
Bruce Barnett (barnett@alydar.crd.ge.com)
Wed, 20 Jul 94 14:10:17 EDT
>The ANSI.SYS driver (ANSI.SYS is the terminal control feature which is
>essentially DEC's VT100 terminal control routines) that comes with MS DOS
>or PC DOS, allows someone to redefine the codes generated by keys.
>I'm not trying to hide what the command sequence is, I just don't
>remember.
I do.
The DEC VT100 manual says sending an ASCII "ENQ" (octal 5)
character to a vt100 terminal will cause it to respond with an
answerback message. I don't know how to program a PC with a custom
message, but the original terminal did not allow programmatic method.
It had to be done using a special setup screen on the terminal.
Years ago I have a vt102 as my primry "workstation".
If someone sat on my console, they could program the answerback
to type "<return>/tmp/funnycommand<clearscreen>"
then they could send a "\005" to my terminal while I was root, and
force me to execute a trojan horse.
This was why I always locked my terminal when I left, and always
checked the answerback message every day.
memories....