What You Need To Know About Boot Sector Viruses

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Harsha Kiran
Written by
Harsha Kiran

Updated · Nov 17, 2023

Harsha Kiran
Founder | Joined March 2023 | LinkedIn
Harsha Kiran

Harsha Kiran is the founder and innovator of Techjury.net. He started it as a personal passion proje... | See full bio

April Grace Asgapo
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April Grace Asgapo


April Grace Asgapo
Joined June 2023 | LinkedIn
April Grace Asgapo

April is a proficient content writer with a knack for research and communication. With a keen eye fo... | See full bio

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Boot Sector Virus is a type of malware that runs during your computer's startup time. It runs before your security defenses perform.

This virus infects, damages, disables, and gains access to your browsers and operating systems.

This article explains Boot Sector Viruses, the mechanism behind them, how to detect such, what the examples are, how to get rid of them, and tips on protecting your device from them.

But before going into those details, here are the important points of this article: 

Key Takeaways:

  • Boot Sector Viruses infect the boot sector of a computer, causing various issues and compromising the system's essential functions.
  • Boot sector viruses spread through physical media like infected floppy disks or USB drives.
  • Signs of a boot sector virus infection include slow performance, blue screen errors, inability to boot, and file encryption or disappearance.

What Can Boot Sector Viruses Do?

Boot Sector Viruses or Boot record infectors infect your computer's storage sector. Some versions of it target the Master Boot Record, a type of boot sector found in hard disks.

Your computer's hard drive has a sector solely responsible for pointing to the operating system so that it can boot; it's called the boot sector.

What is Booting?
Booting is the startup sequence of powering and bringing up a computer's operating system. It involves loading the BIOS, or the first code executed when the computer system is started.

When an infected floppy disk/USB drive is connected to a computer, it executes malicious code into the startup section of a disk. Once infected, the disk may become unbootable.

The virus takes control whenever you turn on your computer. When infected, the BIOS can’t longer instruct your computer's basic functions. 

This situation slows down your operating systems, causes retrieval problems, and prevents your computer from booting.

The Boot Sector Virus can be harmful, but fortunately, there are ways to detect it.

Good to know!

BIOS program instructs your computer's basic functions like keyboard control and, most importantly, boot.

Detecting Boot Sector Viruses on Your Device

The boot sector is the one that controls the basic booting process of a computer, so it can be a challenge to detect. Often, antivirus software is not able to detect boot sector viruses. 

While Boot Sector Viruses try to stay under the radar, they don’t go unnoticed. 

Here are red flags to watch out for when detecting if a boot sector virus has gained access to your computer:

  • Your computer starts to slow down.
  • Your computer boots to a blue screen.
  • Your laptop won’t boot.
  • Your laptop suddenly becomes unstable.
  • You’ll only see texts on a black screen with an error message saying “Invalid Boot Disk,” "Invalid System Disk," or “No Boot Device Found.”
  • Your files start to get encrypted.
  • Your files suddenly disappear.

You should watch for the above signs, as one or two may happen with Boot Sector Viruses. 

Fun fact!

The effect of viruses can range from being mildly invasive to downright destructive, so knowing how to get rid of viruses fast is essential. 

Boot Sector Virus Examples

While boot sector viruses are relatively uncommon nowadays, they played a significant role in the evolution of computer malware. 

The table below shows the most common examples of boot sector viruses. 

Virus Name


Year Created

Method of Spread


Elk Cloner

A non-malicious virus was created as a prank by a high school student. Affected Apple II systems.


Spread via floppy disks

Displayed a poem on every fifth boot from an infected disk.

“Elk Cloner: The program with a personality

It will get on all your disks.

It will infiltrate your chips.

Yes, it’s Cloner! 

It will stick to you like glue.

It will modify ram too.

Send in the Cloner!”


A non-malicious virus created by a student. Infected floppy disks with multiple files.


Infected the boot sector of floppy disks

Rendered disks unbootable and displayed the text "Your PC is now Stoned!"


A virus that infected the hard drive's boot sector. Named after the sculptor Michelangelo Buonarroti.


Infected the Master Boot Record (MBR)

Reformatted hard disk sectors every year on March 6, rendering the hard drive useless. 

Boot sector viruses like Elk Cloner, Stoned, and Michelangelo left their mark on the history of computer viruses. Created as pranks or experiments by individuals, these viruses showcased various methods of spreading and infecting systems.

Understanding these types of viruses can help you take the necessary steps to eliminate them. 

Getting Rid Of Boot Sector Virus

As mentioned, dealing with a boot sector virus can be challenging. REGULAR antivirus programs may not have access to the Master Boot Record (MBR), which may not detect a boot sector virus. 

Several effective methods exist to eliminate this persistent malware and protect your computer from further harm.

Here are a few such methods:

  • Using a bootable antivirus disk. A bootable antivirus disk can help detect and clean malware infections outside an infected operating system. Some antivirus programs even examine your computer without launching Microsoft Windows.

Bootable Antivirus disks such as the Norton antivirus rescue set can be a great tool to eliminate a boot sector virus. There are also other free boot sector removal software that you can choose from. 

  • Using the DOS SYS command. DOS, or disk operating system (DOS), is an operating system that runs from a disk drive. A “DOS SYS” command copies your system files into another disk, allowing the second drive to be bootable.

If you are certain that it doesn’t encrypt the Master Boot Record (MBR), you can use the DOS SYS command to restore the bad sector.


This command only works if you are sure the virus has only affected the boot sector and your current boot sector is not encrypted.

Protecting your device from the Boot Sector Virus is much easier than getting rid of it. Remember to take proactive steps to ensure your device is clean from infection. 

Protecting Your Device from Boot Sector Virus

Current operating systems include protection against Boot Sector Viruses, but it’s always better to have added protection. 

  1. Avoid unfamiliar USB devices: Boot sector viruses often spread through USB devices, so be cautious when plugging in unfamiliar ones.
  2. Use and update antivirus software: Install reliable and keep it current. It should scan for viruses, monitor suspicious activity, and eliminate new threats.
  3. Be cautious with emails: Spam emails can carry boot sector viruses. Avoid clicking on links or opening attachments from unknown or suspicious senders.
  4. Regularly back up your files: Creating backups of your important files allows you to restore them if they get damaged by a boot sector virus.
  5. Be security conscious: Stay informed about cybersecurity and take steps to enhance your security awareness. Consider taking classes or learning about cybersecurity best practices.
  6. Encrypt your disk: Encrypting your disk protects the boot sector from being overwritten by a virus. Full-disk encryption makes your computer unreadable to unauthorized users without the encryption key/password.

Following these simplified guidelines can better protect your device from boot sector viruses and other potential threats.

Wrapping Up

Understanding Boot Sector Viruses and their potential impact on computer systems is crucial for maintaining a secure and functional device. These viruses can infect the boot sector, leading to slow performance, system instability, and data loss. 

While boot sector viruses may be less common today, they have played a significant role in the evolution of computer malware. It's important to be vigilant and take proactive measures to detect and eliminate boot sector viruses.

With the right knowledge and proactive approach, users can safeguard their devices and ensure a secure computing experience.


What is the famous boot sector virus?`

The most prominent Boot Sector Virus type that existed was the Michelangelo virus. The virus reformats hard disk sectors on March 6 every year— the birthday of the famous Renaissance artist Michelangelo.

Can antivirus detect boot sector viruses?

Yes, a bootable antivirus rescue software such as Norton Antivirus rescue kit and Avast rescue disk can help remove boot sector Viruses. But improper removal can result in an unbootable system and an inaccessible drive.

How do I know if I have a boot sector virus?

Some signs may indicate the presence of a Boot Sector Virus. Running an antivirus solution or malware scan are sure ways to detect it.


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