Malware is the most common type of malicious software that affects businesses and there are tens of thousands of malicious programs detected every day. However, not all malware types act in the same way. 

There are also self-replicating, network-destroying worms, and ransomware that can shut down an entire system and keep your data in storage. A single malware assault has the potential to cause your company to suffer enormous losses if you’re not vigilant.

The Most Devastating Malware In History

To help you comprehend the threat posed by malware, we have listed the top 10 computer malware threats of all time.

Melissa

Melissa was first detected in March 1999. It was spread through internet chat rooms and emails providing free access to adult websites. The virus was injected into the victim’s Microsoft Word document using a macro embedded in the document that, upon opening, executes a malicious program. 

If macros are enabled, Melissa will automatically expand to the top 50 contacts in your Outlook address book. The most common symptom of infected devices was mass mailings and server shutdowns.

The purpose of the virus was not necessarily to steal large amounts of data, but rather to infect as many computers as possible. Melissa grew so quickly that she overwhelmed and disabled the email systems of more than 300 Fortune 500 companies globally.

ILOVEYOU

ILOVEYOU also known as Love Letter or Love Bug was first released in May 2000. The malware was sent to hundreds of millions of users in the form of an email with the email subject line “ILOVEYOU”.

Once opened, it infected all the contacts in your Microsoft Outlook address book and overwritten some files on your hard drive. 

With Outlook being the go-to email for most businesses at that time, the popularity of ILOVEY was relatively high. According to a posthumous review, the virus infected more than 45 million computers in 10 days, causing damages of about $10 billion.

Code Red

Code Red is a computer virus that was created to take advantage of serious vulnerabilities in Microsoft’s IIS web server. Code Red reportedly targeted more than 350,000 websites in July 2001, defacing websites with messages such as “Hacked by Chinese.” 

Worms are self-replicating and spread to other computers in the same network, which is what made this attack possible. The damages and costs associated with this attack were valued at $2.7 billion.

Klez

Klez malware was first detected in October 2001. It can take advantage of broken Microsoft email clients and infect anyone in your Outlook address book. The worst part was that it could become a polymorphic virus, meaning that it could mutate its code over time to evade antivirus detection. 

The Klez worm has been developed by a variety of cyber criminals, which makes it very difficult to control. The worm infected about 7 million computers and caused billions of dollars in damages around the world.

Sobig

Sobig was not only a self-replicating worm, but it was also a Trojan horse or malware that masquerades as a benign program. Back in 2003, Sobig sent millions of emails with innocuous subject lines such as “Thank You!” and “Re: Approved.” 

If the worm is downloaded, it will run and collect files from the host machine to look for email addresses to infect. Sobig was so pervasive that it affected computers in North America, Europe, and Asia.

Mydoom

Mydoom malware is the most destructive malware in history. In 2004, Mydoom caused over $38 billion in damages. Like Sobig, this is a variant of a spam email worm that collects email addresses from infected machines and forwards them to itself. 

The worm was also able to leverage an entire network of infected machines to launch DDoS attacks. DDoS attacks involve flooding targeted websites and servers with enough traffic to make them unusable. Mydoom continues to exist and is used in only a small percentage of phishing attacks today.

Sasser

Another computer worm, Sasser, was released in 2004 and targeted computers running Windows XP or Windows 2000. It spread rapidly due to a vulnerability in the LSA Subsystem Service that manages user credentials and logins. 

Millions of computers were affected by the worm, causing them to display blue screens and crash, forcing many companies to suspend their operations until the virus was contained.

Zeus

Zeus is a Trojan horse that is meant to steal bank account information and passwords belonging to individuals. It was first detected in 2007 and attached infected devices to a botnet, which is a large computer network run by hackers. 

The botnet was used by cybercriminals to take money from major companies and banks. While the financial impact of the Zeus Trojan has been documented at approximately $70 million, experts believe that recovery costs could be much higher.

Stuxnet

Stuxnet, also known as the Stuxnet computer worm, is a malicious software program that infects computers using USB drives. Stuxnet was first detected in 2010 and is mainly used in the context of cyber warfare. The attack focused on industrial control systems that are used to run nuclear power plants as well as other industrial facilities.

Because Stuxnet was so strong, it was able to physically harm Iran’s nuclear centrifuges and exert control over them. Stuxnet may not have caused as much economic destruction as other malware, but it did demonstrate how advanced malware can cause physical damage to critical infrastructure.

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WannaCry

WannaCry is a type of ransomware that was first detected in May 2017. The WannaCry ransomware was similar to other ransomware in that it encrypts the files on the infected computers and demands a ransom from the victims.

What made it stand out, however, was its ability to spread quickly across computer networks by taking advantage of weaknesses in legacy Windows operating systems.

Ransomware has affected more than 230,000 computers across 150 countries and caused hundreds of thousands of dollars in losses to hospitals and large businesses. WannaCry has caused more than $4 billion in damages, and new ransomware variants are being created based on WannaCry’s code.

What can you do against future malware threats?

Cybersecurity is more important than ever due to the ever-changing nature of malware threats and its global impact. In other words, you need strong network security, strong antivirus solutions and a strong backup infrastructure.

In addition, you need to keep your systems up to date and have a good level of cyber hygiene in place to prevent malware from making its way into your systems.