From the Linux Virus Writing HOWTO:
“An astonishing number of people think that viruses require
secret black magic. Here you will find simple code that patches
other executables. But since regular users can’t overwrite system
files (we are talking about serious operating systems here) that is
not even half the journey. To make any impact you need root
permissions. Either by tricking the super user to run your virus,
or combining it with a root-exploit. And since all popular
distributions come with checksum mechanisms, a single command can
detect any modification. Unless you implement kernel-level stealth
functionality?“I do believe that free software is superior, at least in regard
to security. And I strongly oppose the argument that Linux viruses
will flourish once it reaches a critical mass of popularity. On the
contrary I question the credibility of people whose income relies
on widespread use of ridiculously insecure operating systems.“This document is my way to fight the FUD. Use the information
presented here in any way you like. I bet that Linux will only grow
stronger…”