The virus that executes when a computer starts is called a boot sector virus.

Quick Scoop: Direct Answer

When people ask, “viruses which executes when computer starts is…?” the standard textbook / exam-style answer is:

Boot sector virus.

This is the type of virus that infects the boot sector or master boot record (MBR) of a disk so its code runs automatically as soon as the system starts, often even before the operating system fully loads.

What is a Boot Sector Virus?

  • It infects the boot sector or MBR/VBR (the part of a disk that tells the computer how to start the operating system).
  • Its malicious code is loaded during the boot process , so it runs every time the computer starts.
  • Because it runs so early, it can bypass or interfere with security tools that load later.

A common exam MCQ phrase is literally:
“Viruses which execute when a computer starts are called boot sector viruses.”

Why Boot Sector Viruses Are Dangerous

  • They can make the system fail to boot , show errors like “Missing Operating System,” or cause crashes.
  • They may spread to other disks (USB, external drives) used for booting.
  • They often require special tools or recovery media to remove, since the normal OS may not even start properly.

Classic examples mentioned in security discussions include older viruses like “Michelangelo” and “Brain,” which targeted the boot sector and activated at startup.

Related Exam Context (MCQ Style)

You’ll often see this question in competitive exams or school tests with options like:

  • Macro
  • Salami sharing
  • File infector
  • Boot sector

The correct option is: Boot sector (virus).

If you’re revising, just remember:

“Runs when computer starts” → Boot sector virus.

TL;DR:
For the query “viruses which executes when computer starts is” , the correct term is boot sector virus.

Information gathered from public forums or data available on the internet and portrayed here.