3.0 COMPUTER SECURITY..
3.1 Define COMPUTER SECURITY
Computer security means protecting our computer system and the information they contain unwanted access , damage, destruction or modification.
COMPUTER THREATS
3.2 Explain briefly the different COMPUTER THREATS to computer security: MALICIOUS CODE, HACKING, NATURAL DISASTER AND THEFT.
I. Malicious code
Malicious code is a computer program that perfume unauthorized process on a computer or network. There are various kinds of malicious code
Virus – A virus is a computer program that is designed to copy itself into the other programs stored in a computer. It attaches itself to the program usually capable of causing great harm to files or other programs on the same computer. A true virus cannot spread to another computer without human assistance.
The most dangerous computer viruses of the 20th century.
a. Morris – It could overwrite the Master Boot Record of the HDD, thus making it impossible for the uses to access the hard disk.
b. CIH ( a . k . a Chernobyl) After being activated, the virus overwrote data on the HDD of the infected PC, making the letter inoperable.
Trojan Horse – Trojan horse is a computer program that performs a useful task while the same time carry out
some secret desctrucive act. The contents of a trojan horse can be a virus or worm.
some secret desctrucive act. The contents of a trojan horse can be a virus or worm.
In Greek mythology, there is a story about the Trojan War. This war lasted many years, as the Greeks could
not penetrate the heavily barricaded city or Troy. So one day, a few of the Greek soldiers brought the people
of Troy a large wooden horse, which they accepted as a peace offering. The horse was moved inside the city
walls, where it sat until the night. After the people of the city had fallen asleep, Greek soldiers jump out of the
wooden horse, opened the gates to their fellow soldiers in, and took over the city.
not penetrate the heavily barricaded city or Troy. So one day, a few of the Greek soldiers brought the people
of Troy a large wooden horse, which they accepted as a peace offering. The horse was moved inside the city
walls, where it sat until the night. After the people of the city had fallen asleep, Greek soldiers jump out of the
wooden horse, opened the gates to their fellow soldiers in, and took over the city.
A Trojan horse is a computer programs that acts as regular programs, such as game, disk utility, and even anti
virus program. But if it runs, this program can do malicious thing to your computer.
virus program. But if it runs, this program can do malicious thing to your computer.
For example, a Trojan horse might appear to be a computer game, but once you double-click it, the program
starts writing over certain parts of your hard drive, corrupting your data.
starts writing over certain parts of your hard drive, corrupting your data.
The Zeus Trojan, called “most dangerous virus ever created” has stolen 675,000 from a British financial
institution. About 3,00 online banking customers have been victims of a computer virus attack that empties
their accounts while showing them fake statements so the scam goes undetected.
institution. About 3,00 online banking customers have been victims of a computer virus attack that empties
their accounts while showing them fake statements so the scam goes undetected.
Logic bomb-A logic bomb is a computer virus or a worm that is designed to activated under certain
condition. An example of logic bomb is a time bomb. It goes out and causes threats at a specific time or date.
e.g
condition. An example of logic bomb is a time bomb. It goes out and causes threats at a specific time or date.
e.g
Friday the 13th – each Friday 13th it deletes all programs in the infected system.
Michelangelo – each march 6th it overwrites the first on hundred sectors of the hard disk with nulls.
Trapdoor-and backdoor. Trapdoor is computer program that open the back door and allow other people to
have unauthorized access to your computer over internet. Backdoor functions can include: sending/receiving
files, launching/deleting files, executing files and deleting data.
have unauthorized access to your computer over internet. Backdoor functions can include: sending/receiving
files, launching/deleting files, executing files and deleting data.
Worm-A program that copies itself and spread through the network.
A computer infected by a virus, worm, or Trojan horse often has one or more of the following symthoms:
i. Screen displays unusual message or image.
ii. Music or unusual sound plays randomly.
iii. Available memory is less than expected.
iv. Existing programs and files disappear.
v. Files become corrupted.
Hacking
Hacking
Hacking refer to unauthorized access to the computer system by a hacker. A hacker is a person who access a computer or network illegally. A hacker has advanced computer and network skills.
Nature Threats (Act of god)
Computers are also threatened by natural or environmental disaster. Examples of natural and environmental disasters are flood, fire, earthquakes, storm, tornados, excessive heat and inadequate power.
Theft
Theft
Two types of theft
a. Computer is used to steal money, goods, information and resources.
b. Stealing of computers especially notebook and PDA.
Three approaches to prevent theft:
Three approaches to prevent theft:
a. Prevent access by using locks, smart card or password.
b. Prevent portability by restricting the hard ware from being moved.
c. Detect and guard all exits and record any hardware.
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