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 becomesvery 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 abig@boss.comreturn 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.

3) ILOVEYOU
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 .

4) 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.

5) 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.

These are the 5 worst computer viruses of all time. Hope you like the post, share it as much as possible. We love comment here.
Thank's for reading my article