Introduction to Virus

Computer viruses are perceived as a threat to both business and personal. Virus is a self-replicating program that produces its own code by attacking copies of itself into other executable codes. Operates without the knowledge or desire of the computer user.

Characteristics of a Virus

Virus resides in the memory and replicates itself while the program where it is attached is running. It does not reside in the memory after the execution of the program. It can transform themselves by the changing code to appear different.

It hides itself from detection by three ways.

  • It encrypts itself into the cryptic symbols.
  • It alters the disk directory data to compensate the addition virus bytes.
  • It uses stealth algorithms to redirect disk data.

Working of virus

Triggers evens and direct attack are the common mode which cause a virus to “go off” on a target machine.

Most viruses are operate in two phases

 1. Infection phase

  • Virus developers decided when to infect the host system’s program.
  • Some infect each time they are run and executed completely ex direct virus
  • Some virus code infect only when users trigger them which includes a day, time or a particular event ex TSR virus.

2. Attack phase

  • Some virus have trigger events to activate and corrupt systems
  • Some virus have bug that replicate and perform activities like file and deletion and increasing the session time.
  • They corrupt the targets only after spreading completely as intended by their developers.