Mydoom, also known as Novarg, is a computer worm that emerged in 2004, causing widespread damage through self-replication and mass emailing. It targets Microsoft Windows operating systems and spreads through email attachments and peer-to-peer networks. Once activated, Mydoom can grant unauthorized access to the infected device, launch denial-of-service attacks, and distribute additional malware.

Key Takeaways

  1. Mydoom is a notorious computer worm that was first discovered in 2004 and is considered one of the fastest-spreading email worms in history.
  2. The primary purpose of Mydoom was to launch distributed denial-of-service (DDoS) attacks, infect local files, and open backdoors on infected machines, thereby allowing attackers to gain unauthorized access.
  3. Mydoom primarily spreads through email attachments and peer-to-peer (P2P) file-sharing networks, making it crucial for users to practice caution when opening email attachments and downloading files from untrusted sources.


Mydoom is an important technology term because it refers to a computer worm that caused major disruption and damage to computer networks around the world when it first appeared in 2004.

Known as one of the fastest-spreading email-based worms in history, it compromised the security and integrity of both individual and corporate systems by exploiting various system vulnerabilities.

The worm not only opened backdoors for unauthorized access, but also initiated distributed denial-of-service attacks targeting various websites, thereby disrupting operations and causing significant financial losses.

Mydoom serves as a critical reminder of the importance of robust cybersecurity practices and regular system updates to stay protected from such nefarious activities.


Mydoom, a notorious computer worm, gained infamy in the early 2000s as one of the fastest-spreading email-based malware programs. Its primary purpose, much like other worms, was to infect vulnerable computers and cause disruption to networks.

Mydoom was primarily designed to launch distributed denial of service (DDoS) attacks by overwhelming targeted systems with data requests, rendering them inaccessible to legimate users. This cyber threat exploited security flaws on certain Windows systems, allowing it to infect millions of devices, causing significant damage to both individual users and corporate networks.

The underlying purpose of Mydoom, apart from causing disruptions and damage, was often attributed to financial motives. Hackers used this worm to build botnets, which are networks of infected computers that can be remotely controlled for malicious activities.

These botnets were then used to initiate spam campaigns, conduct further DDoS attacks or distribute additional malware strains at the attacker’s behest. By deploying Mydoom, cybercriminals could effectively assert control over vast networks of compromised devices, often renting out these botnets to other hackers, consequently establishing an illegal yet lucrative business model.

Examples of Mydoom

Mydoom is a computer worm that caused widespread damage when it was first unleashed in

It is considered one of the fastest-spreading and most destructive worms in history, as it infected millions of computers worldwide. Here are three real-world examples involving the Mydoom worm:

Mydoom.A (2004): Mydoom.A, also known as Novarg, was the first variant of the Mydoom worm. It was released on January 26, 2004, and targeted Microsoft Windows computers. The worm spread through email attachments with spoofed Sender addresses. Once executed, it opened a backdoor, allowing remote access to the infected machine. It also initiated a Distributed Denial of Service (DDoS) attack on the website, belonging to the SCO Group, a software company that was involved in a legal dispute with Linux. This attack crippled the company’s website for several days.

Mydoom.B (2004): A few days after the release of Mydoom.A, a new variant called Mydoom.B (or Doomjuice) appeared. This version had similar features, but its primary target was Microsoft’s website ( It launched a DDoS attack against the site, causing outages and slow performance. To evade detection, Mydoom.B also blocked access to various antivirus and security websites, making it difficult for users to remove the worm.

Mydoom’s Impact on Email Systems: Mydoom was highly successful in infecting millions of computers globally and congesting email servers. As the worm propagated by sending an email with an infected attachment, it resulted in numerous unwanted messages, causing network slowdowns and system crashes, and affecting business operations worldwide. The estimated economic impact of the Mydoom worm and its variants is around $38 billion, making it one of the costliest malware attacks in history.

Mydoom FAQ

What is Mydoom?

Mydoom is a computer worm that affects Microsoft Windows operating systems. First discovered in January 2004, Mydoom quickly spread through email attachments, causing significant damage and making it one of the fastest propagating worms in history.

How does Mydoom spread?

Mydoom typically spreads via email attachments that contain infected files. Once the user opens the attachment, the worm replicates itself and sends copies to the victim’s email contacts. It can also propagate through peer-to-peer file-sharing networks and backdoor channels created by other malware.

What are the symptoms of a Mydoom infection?

Some common symptoms of a Mydoom infection include slow internet connection, frequent system crashes, increased network traffic, and unauthorized access to your computer. Additionally, you may notice a sudden increase in the number of emails being sent from your account, as well as errors or bounce-back messages from email servers.

How can I protect my computer against Mydoom?

To protect your computer against Mydoom and similar threats, always keep your operating system and antivirus software up to date. Avoid opening email attachments from unknown senders and exercise caution when downloading files from the internet. Regularly scan your computer for malware and use a firewall to block suspicious network activity.

How can I remove Mydoom from my computer?

If you suspect that your computer is infected with Mydoom, run a full system scan using a reputable antivirus program. Most antivirus software is capable of detecting and removing Mydoom. After the initial removal, ensure that your security software is up to date and follow best practices for preventing future infections.

Related Technology Terms

  • Email Worm
  • Mass Mailer
  • Denial-of-Service (DoS) Attack
  • Backdoor
  • Computer Virus

Sources for More Information

  • Symantec – A leading cybersecurity company that provides information on major security threats, including Mydoom.
  • Kaspersky – A well-known cybersecurity and anti-virus provider that covers the Mydoom worm in detail.
  • McAfee – A global security software company that shares insights on the Mydoom malware and its variants.
  • TrendMicro – A popular cybersecurity firm that offers in-depth information about the Mydoom worm and its impacts.

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