2. Computer Security
Means protecting our computer system and the
information they contains against unwanted access,
damage, destruction or modification.
3. Computer Threads
Malicious code
Is a computer program that perform unauthorized processed an a
computer or network
There are various kinds of malicious code:
i) Virus
ii) Trojan horse
iii) Logic bomb
iv) Trapdoor
v) Worm
Differences between worm and virus are:
WORM VIRUS
Operates through the network Spreads through any medium
Spread copies of itself as a stand alone Spread copies of itself as a program
program that attaches to other program
4. A computer infected by a virus, worm or trojan
horse has one or more of the following symptoms:
Screen displays unusual message or image
Music or unusual sound plays randomly
Available memory is less than expected
Existing programs and files disappear
Files become corrupted
5. Hacking
Hacking refer to unauthorized access to the
computer system by a hacker
A hacker is a person who accessed a computer or
network illegally
A cracker also is someone who accessed a
computer or network illegally but has to intend of
destroying data, stealing information or other
malicious action
6. Nature threads
Computers are threatened by natural or
environmental disaster. Be it at home, stores, offices
and also automobiles
Examples: flood, fire, earthquakes, storms,
tornados, excessive heat and inadequate power
7. Theft
Two types of theft
i) Computer is used to steal money, goods, information
and resources
ii) Stealing of computers especially notebook and PDA
3 approaches to prevent theft:
i) Prevent access by using locks, smart card or
password
ii) Prevent portability by restricting the hardware from
being moved
iii) Detect and guard all exits and record any hardware
8. Security Measures
Security measures are measures taken as a
precaution against theft or espionage or sabotage
or possible danger or failure
Usually we use antivirus, cryptography, firewall and
data backup to protect sensitive information
9. Anti-virus
Is a utility program that we use to protect a computer
against viruses by identifying and removing computer
viruses found in the computer memory, computer storage or
incoming e-mails files
Examples:
Norton Antivirus
AVG
Kaspersky
Bitdefender
Nod32
10. Anti-spyware
Is a utility program that we use to protect the
computers from spyware
Spyware is a software or computer program that is
designed secretly record and report an individual’s
activities on the Internet
Examples:
Spybot Search and Destroy
Ad-ware
Spyware Blaster
11. Firewall
Is a piece of hardware or software which functions in
a networked environment to prevent some
communications forbidden by security policy
We use firewall to prevent hacking (access is the
use of a computer or network without permission)
Types of firewall
SCREENING ROUTERS PROXY GATEWAY GUARD
simplest • some what complex • most complex
sees only addresses and • sees full text of • sees full text of
service protocol type communication communication
12. Backup
Is a utility program that makes copy of all files that
have been saved onto a disk
Backup data is important when original data is
corrupted
When data corrupted, it is spoilt and cannot be
properly used because it has become changed in
wrong ways
13. Cryptography
Is a process of transforming plaintext into cipheart
then back again
Encryption is a process of converting plaintext into
cipertext. Decryption is the process of converting
ciphertext into plaintext
Encryption was used only by intelligence services,
militaries and banks. We use cryptography to
secure the information and prevent hacking or
unauthorized access.
15. Human aspects
The user and also the intruder of a computer system
The hardest aspects to give protection
The most common problem of human aspect security
is the lack of achieving a good information
security procedure
