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Secretly Monopolizing the CPU Without Being Root
An anonymous reader writes "This year's
Usenix security symposium
includes a
paper
that implements a "cheat" utility, which allows any non-privileged user to
run his/her program, e.g., like so 'cheat 99% program'
thereby insuring that the programs would get 99% of the CPU
cycles, regardless of the presence of any other applications in the
system, and in some cases (like Linux), in a way that keeps the program
invisible from CPU monitoring tools (like 'top'). The utility exclusively
uses standard interfaces and can be trivially implemented by any
beginner non-privileged programmer. Recent efforts to improve the
support for multimedia applications make systems more susceptible to
the attack.
All prevalent operating systems but Mac OS X are vulnerable, though by
this kerneltrap story,
it appears that the new CFS Linux scheduler attempts to address the
problem that were raised by the paper."
I run several websites off of a single host. If I need to login to do maintenance during peak hours, I'm slowed by Apache and MySQL. This would be a nice utility if it were wrapped into SUDO.
I'd rather you do it wrong, than for me to have to do it at all.
The gnome desktop for years has been hiding processes that h0rk the cpu.
Using up 99% of the CPU's easy!
#include
int main(int argc, char *argv[])
{
while (1) {}
return 0;
}
Summation 2
This year's Usenix security symposium includes a paper that implements a "cheat" utility, which allows any non-privileged user to run his/her program, e.g., like so 'cheat 99% program' thereby insuring that the programs would get 99% of the CPU cycles, regardless of the presence of any other applications in the system, and in some cases (like Linux), in a way that keeps the program invisible from CPU monitoring tools (like 'top').
Next up, a virus which senses bad grammar and punishes you by using 99% of your CPU. Seriously, somewhere a middle school English teacher is crying, and doesn't know why.
Please help metamoderate.
If you reply, do so only to what I explicitly wrote. If I didn't write it, don't assume or infer it.
You gun-toting marxist redneck zealot astroturfers make me sick!
We had a user who insisted on abusing the "nice" command, to run his jobs at a higher priority. Pleading and cajoling didn't work, so we decided to get creative.
We changed nice so that whenever this particular user ran it, it lowered his priority by exactly as much as he was attempting to raise it.
He stopped coming to work soon after that. I suppose he had the last laugh though -- NYIT continued to pay him for another six months.
Thad
I love Mondays. On a Monday, anything is possible.
My mother is a gun-toting marxist redneck zealot astroturfer, you insensitive clod!
The creator of this post (Jacob Smith) hereby releases it, and all of his other posts, into the public domain.
This is an outrage. You cannot 'sue' without lawyerd! What about the required functionality of 'sue --counter' and 'appeal'?!
The only change I can believe in is what I find in my couch cushions.
It's a baseball bat.
It doesn't even matter if these CPU-hogging processes can hide from "top" - you should already be making regular rounds of your users, even the ones you haven't caught doing anything wrong. Nobody questions it when you tell them, "You know what you did." Not when you're the one with the bat.
it works by avoiding running during the exact moment of a clock tick (which would be the moment when CPU usage...
--Uhm... (looks at watch...) Say, I really don't have time for wordy summaries... could you maybe cut this down into about 10 words or less? Hurry it up! I ain't got all day!
"They said I probly shouldn't fly with just one eye," "I am Bender. Please insert girder."
What a scary, scary thought...
it run when OS not looking
Like in Superman 3.
Wrong n00b!
May contain traces of nut.
Made from the freshest electrons.