Our Rundown of the Top Five Worst Computer Viruses

Our Rundown of the Top Five Worst Computer Viruses

Just a few months ago, the NHS was hit by a ransomware attack that affected more than 200,000 individuals in 150 countries. Using malware called ‘Wanna Decryptor’ or ‘WannaCry’, the virus sent both the NHS and the online community into complete meltdown. With computer viruses and other hacking efforts on the rise, will businesses and individuals ever be safe online? We take a look back at five viruses that nearly broke the internet and touch upon how companies can protect themselves.

Not a virus for the fainthearted, ‘Heartbleed’ – a security bug – sent both the internet and mobile community into a frenzy in 2014, with a reported half-a-million websites estimated to be affected. The bug managed to obtain chunks of information including usernames, passwords, and other private data, which led to major blogs, cloud accounts, emails and social networks being infected. Although Heartbleed is now being monitored, businesses and individuals are still advised to take precaution by implementing sensible security measures, such as regularly updating passwords and installing additional back-up protection in case they fall victim.

One of the most infamous in the malware family, ‘CryptoLocker’, a form of Trojan horse ransomware, targeted Microsoft Windows computers in an attack that occurred between September 2013 and May 2014. Over the course of the year, the virus spread through email attachments and encrypted users’ files so that they were unable to access them without paying a decryption fee. Hackers demanded thousands of pounds in return for the key, but luckily the 500,000 affected users were able to recover their files after security experts “got lucky” and managed to create an online portal that provided access to the stolen information after obtaining a database of the virus’ victims, according to the BBC.

In 1999, a virus created by computer programmer David Smith called ‘Melissa’, infected over one million users across the US by distributing itself as an email attachment that, when opened, deactivated a number of protections in Word 97 and Word 2000. The virus also infected Microsoft Outlook which caused the software to send the virus on to the first 50 people in the user’s online address book.
As a result of the virus’ ability to spread itself across multiple devices, on Friday 26 March 1999 Microsoft Corporation was forced to shut down the incoming email function on the software.

But, it wasn’t too long before Smith was tracked down by the authorities and sentenced to 10 years in prison – although he only served 20 months – after pleading guilty to causing more than $80 million in damage to businesses across North America.

Despite security software becoming more sophisticated in its ability to detect cyber-attacks, macro viruses such as Melissa continue to affect devices across the globe, making it vital that proper IT protection is implemented by companies to prevent cybercriminals causing huge financial damage. Learn more about the different security measures you can take in our ‘Ransomware: What is it and what can businesses do to protect themselves’ blog post.

At the time, technology writers and experts debated whether it could be an April Fool’s joke, but nevertheless the computer worm ‘Conficker’ left its mark on the IT world when it first targeted Microsoft Windows operating systems in 2008. Using vulnerabilities in the software to create one of the biggest botnets – a network of “robot” computers used to scam users – in the history of the internet, Conficker managed to affect millions of personal and business computers, including the French Navy’s IT network Intramar. The Conficker worm inflicted an estimated $9 billion in damages to computers around the world.

Given its name, its unsurprising that ‘Mydoom’ has been hailed as one of the most dangerous computer worms ever released. Recorded as the fastest-spreading email-based worm in internet history, Mydoom affected computer networks of individuals and global conglomerates such as Microsoft and Google in 2004 via an email attachment that, quite literally, opened a can of worms by spreading the virus via other email addresses. According to the BBC, the virus was deemed particularly malicious as it had the capability to open “back doors” to computers, further highlighting the need for businesses and individuals to not only be more vigilant to suspicious emails, but to also implement appropriate security measures.

What can businesses do to protect themselves?
In a society where cybercriminals and hacking software are becoming more sophisticated, businesses can no longer deny the need for robust IT security measures. One of the most effective and reliable things businesses can do is to incorporate a cyber security system to fully protect their online data. We advise that businesses regularly update their anti-virus software and use programmes like C-Assure 365 – our Office 365 backup programme – to provide additional and guaranteed long-term security across 100 per cent of data. For more IT security advice, you can speak with one of our friendly specialists today by calling 03333 708 090.