Top 10 Most Dangerous Computer Viruses Of All Time

Top 10 Most Dangerous Computer Viruses Of All Time

Top 10 Most Dangerous Computer Viruses Of All Time

Top 10 Most Dangerous Computer Viruses Of All Time: Virus in computer system truly means a big nightmare. A virus is like cancer for computers which slowly destroys the whole system. Different viruses cause different damage, and some of them force the user to erase precious data, change data without the user’s knowledge, suspend the network and some of it can even destroy the hardware.

Some time ago, hackers had the intention of invading the data or account of others. Nowadays, hackers have become professionals and their ambitions have reached a higher level. The professional’s goal is to make a hole in technology since instead of just looking at one, they can get millions of accounts by finding a single loophole in algorithms.

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Top 10 Most Dangerous Computer Viruses Of All Time

However, just to make you aware of how dangerous viruses can be, here we are going to explore 10 worst computer viruses of all time. So, let’s check out the most dangerous viruses of all time.

1) MyDoom

MyDoom became the fastest e-mail distributed worm in 2004. The virus creates a background port on the operating system, allowing unauthorized users to access the system. MyDoom can also fake emails so that it becomes very difficult to trace the origin.

Like other viruses, MyDoom searches for email contact in the mailing list, and through the infected computer, it browses the search sites behind emails of future victims.

MyDoom Virus have caused the estimated damage of around $38 billion.

2) Sobig

Sobig was a Trojan horse that infected millions of Microsoft Windows computers connected to the Internet in 2003. Sobig had 6 total variants. Recipients receive the Sobig virus via e-mail, with a [email protected] return address. All these emails consist of .pif extension files. Once downloaded, it copies itself to the windows folder as Winmgm32.exe which allows the operating system to be used as a port of spammers.

The virus caused an estimated damage of around $37 billion.

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3) Klez

Klez is a computer worm that came into existence in 2001. It travels through e-mail and infects the Microsoft Windows computer by exploiting the vulnerability in the IE Trident layout machine.

This virus can even disable the antivirus program and impersonate it as a virus removal tool. Like other viruses, it makes copies of itself and distributes it to the user’s contacts. There are 3 variants, and the virus is not yet completely dead.

The virus caused an estimated damage of around $19 million


Back in 2000, millions of people made a big mistake by opening a nice and innocent-looking e-mail, I Love You. A program that can replicate and steal the user’s password, and send it to the hacker’s email address.

The virus adds a new file to registry keys, replaces the image files, and used to send the copies to all the email addresses specified in the Windows list.

The Virus caused an estimated damage of around $15 billion

5) Conficker

Conficker is a computer worm that first appeared in 2008. It targeted Microsoft Windows bug and dictionary attacks on the administrator’s password to navigate while forming a botnet.

The infected computer sends special RPC request to force buffer overflow and execute shellcode on a target system. Conficker virus runs an HTTP server on a port from 1024 to 10000, to download a copy of the virus in DLL format which then later joins svchost.exe.

The virus caused an estimated damage of around $9 billion

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6) Code Red

Code Red was a computer worm that emerged in 2001. After 2 weeks, Code Red II appeared on the Internet. Code Red exploited the Windows 2000 and Windows NT system vulnerability.

Code Red exploited the buffer overflow problem, that is, when an operating system receives more data than its buffers can handle, it simply starts overwriting adjacent memory. The virus affected more than 2 million users worldwide making them format the hard drive and reboot.

The virus caused an estimated damage of around $2.7 billion

7) Melissa

Melissa Virus was developed by a man named David L. Smith in the year 1999. The virus is based on Microsoft Word. Melissa automatically extends through an e-mail attachment. Once the attachment named list.doc is opened in MS Word or Outlook, it is forwarded to the first 50 contacts in the address list, along with the message “Here is the document you requested … do not show it to anyone else “.

It does not destroy personal files or data present on the hard drive, but it was strong enough to suspend the entire network. For creating Melissa, David received 20 months of imprisonment and a fine of $ 5000.

The virus caused the estimated damage of around $1 Billion

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8) Sircam

Sircam is a computer worm that spreads through e-mail, looking at Microsoft Windows. The same was notable during the outbreak due to the manner of the method of propagation. The files were randomly selected on an infected computer, usually .doc and XLs, replaced with virus code and sent to addresses present in the host address list.

It is also propagated via open network sharing. The virus simply scanned the network with shared drives and copied the network to the open-drive machine without password protection. Sircam is ninth in this selection.

The virus caused the estimated damage of around $1 Billion

9) SQL Slammer

Also known as SQL Sapphire, it arrived on January 25, 2003, and slowed down internet traffic around the world, and caused the denial of service on some internal hosts. It also toppled several crucial servers and affected the Bank of America’s ATM, and 911 service in Seattle. Overall, it affected around 200,000 computers worldwide

The virus caused the estimated damage of around $800 million

10) Sesser and Netsky

Both viruses were created by a German computer student just 18 years old. Sven Jaschan used the two to exploit vulnerabilities in Windows XP and 2000 systems through the buffer overflow. The difference between viruses was how they mirrored the network.

Sasser invaded any random IP as soon as it could infect a vulnerable system. It slowed down the system and made it difficult to reboot. Netsky virus invaded via e-mail after users downloaded an attached file of 22,016 bytes.

The virus caused the estimated damage of around $700 million

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These are the 10 worst computer viruses of all time. Hope you like the post, share it as much as possible.

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