Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
One question for Linux gurus: Why is it that Linux/Ubuntu is said to be so secure..? Is it because simply no viruses are programmed for Linux (like Macs), or is there something special about Linux architecture/core that makes it less vulnerable to attacks..?
The most important part involves the history of Unix (Linux is a Unix-alike), Which is forty years old. Unix has had privilege separation and emphasized multi-user environments for over thirty years, While the system for privilege separation is rather simple by today's standards, every program on any modern Unix (or Linux) grew out of the Unix multi-user culture. Programs respect it. They don't require Root (Admin) privileges to run. They don't expect a single user environment.
Like I said, this user/group/all privilege system is too simple to be comprehensively secure with all the sophisticated attack methods people use these days. SELinux and AppArmor are additional systems which sit on top of the old u-g-a system and which sandbox processes. Ubuntu uses AppArmor for a lot of applications.