I'm reminded of a story I read a while back (around 20 years ago) about engineers pointing out a security flaw in a vendor's Unix system, which the vendor did not take seriously. So they wrote a pair of programs: Falstaff and Othello, if I remember correctly... where if you killed one, the other would output to the console something to the effect of "I'll save you!" and would resurrect the other program, making it extremely difficult to eradicate from the system.
I've been trying to find this... anyone have a reference to the original?
I wonder if it's a bit apocryphal. I feel sure I've also read a version where the two processes were called “sheriff” and “deputy”, and you suggested yet a third naming scheme.
“Back in the mid-1970s, several of the system support staff at Motorola discovered a relatively simple way to crack system security on the Xerox CP-V timesharing system. Through a simple programming strategy, it was possible for a user program to trick the system into running a portion of the program in ‘master mode’ (supervisor state), in which memory protection does not apply.
[…]
Months passed. The Motorola guys pestered their Xerox field-support rep, to no avail. Finally they decided to take direct action, to demonstrate to Xerox management just how easily the system could be cracked and just how thoroughly the security safeguards could be subverted.
They dug around in the operating-system listings and devised a thoroughly devilish set of patches. These patches were then incorporated into a pair of programs called ‘Robin Hood’ and ‘Friar Tuck’. Robin Hood and Friar Tuck were designed to run as ‘ghost jobs’ (daemons, in Unix terminology); they would use the existing loophole to subvert system security, install the necessary patches, and then keep an eye on one another's statuses in order to keep the system operator (in effect, the superuser) from aborting them.
One fine day, the system operator on the main CP-V software development system in El Segundo was surprised by a number of unusual phenomena. […]
Naturally, the operator called in the operating-system developers. They found the bandit ghost jobs running, and killed them... and were once again surprised. When Robin Hood was gunned, the following sequence of events took place:
!X id1
id1: Friar Tuck... I am under attack! Pray save me!
id1: Off (aborted)
id2: Fear not, friend Robin! I shall rout the Sheriff
of Nottingham's men!
id1: Thank you, my good fellow!
Each ghost-job would detect the fact that the other had been killed, and would start a new copy of the recently slain program within a few milliseconds. The only way to kill both ghosts was to kill them simultaneously (very difficult) or to deliberately crash the system.”
I've been trying to find this... anyone have a reference to the original?