Wednesday, October 28, 2009

Lecture 4 : Program Security

Slide 7::Viruses and ”Malicious Programs”

a) Computer viruses has ability to replicate them self i
nto large number of computer. Spread by floppy disk and USB drive or nowadays is through internet.

b) Malicious programs may be installed by ha
nd on a single machine. But may built into software packages. It likes Trojan Horse, Traps Doors and Logic Bombs.

Slide 8Malicious Programs ::

Malicious program split into two:

* Need host program - Trap doors, Logic Bombs, Trojan Horses, Viruses.
*Independent - Bacteria, Worms.

:: Examples of malicious code

1) Trojan Horse - Slide 9 a program which performs a useful function, but also performs an unexpected action.

2) Virus - code segment that replicates and attach to existing programs.
Slide 9Transient - executes when the program that it is attached to runs.
Resident - stay in program when execute, stay till it trigger again.

3) Worm - program that replicates and copy the file/folder it locates.
4) Bacteria - program that replicates itself until fills up all spaces or CPU cycles.
5) Logic Bomb/ Time Bomb - malicious code that activates on an event.
6) Trap Door - written entry point, that cause unwanted users.
7) Spyware - Steal info, see web sites visited, see contents of files, popUp ads, slow down computer and crash the computer too.