Paging Monsters
Paging Monsters
Copyright(c) Management Analytics, 1995 - All Rights Reserved
Copyright(c), 1990, 1995 Dr. Frederick B. Cohen - All Rights Reserved
Problem:
A paging monster is a program designed to force the operating
system to slow down by forcing as many pages as possible out of memory
every time it is run. A typical paging monster loops, writing one byte
to each of 1,000 or more different memory pages. If we combine the
paging monster with a worm, we can sometimes almost halt all other
processing. As a side effect, we tend to exercise some of the less
tested parts of the operating system under high stress conditions, thus
bringing out latent programming or design errors that would otherwise
show up very rarely. This can cause anything from a crash to a
protection failure.
Prevention:
Paging monsters cannot be prevented in and modern UNIX system.
Detection:
Paging monsters can be detected by the characteristic system thrashing.
Cure:
The cure for paging monsters is to kill the offending processes.
If the paging monster is also self-replicating, we typically have to
reboot the system.