Computer Security Threats

Computer Security Threats

1. Virus or Malicious code

Malicious codes are mischievous programs which are used to disrupt the normal operation of computer systems. They usually travel from one computer to another through floppy or portable disks, CD-ROMS, emails and file downloads.

Types of Malicious Code

• Worms (They are usually small programs, having the capability of spreading themselves between systems and often overwhelming network and system resources while doing so.)

• On the other hand viruses attach themselves to a piece of code and are spread as that code is executed. For example, a pirated game may contain a Trojan Horse and may operate malicious operations in the background while the user is playing.

Lifecycle of computer viruses

1. The dormant phase

2. The propagation phase

3. The triggering phase

4. The execution phase

Virus types

1. Transient (Parasitic) Virus: (most common type of virus)

2. Memory Resident Virus :(Virus may infect every program that executes)

3. Boot Sector Viruses: (infect important files located in boot sector and spreads when the computer system is switched on.)

Example of Computer Viruses

1. The Melissa Virus (March, 1999)

2. The Love Letter Worm (May, 2000)

3. The Code Red Worm (July, 2001)

4. The Slammer Worm (January, 2003)

Antivirus steps to eradicate a virus

1. Detection of the infected files and location of the virus.

2. Identification is used to spot and classify the specific virus.

3. Removal process eliminates the virus from all infected systems. This means that the virus cannot spread further.

4. Recovery is done to restore the computer system to its