Computer viruses can be scary and could cause extensive damage to your innocent device.
It can significantly disrupt your system's performance and has the potential to wipe out everything on your hard drive. Viruses are malicious software programs that, when executed, replicate copies of themselves (possibly modified) into other computer programs, data files, or the boot sector of the hard drive. When this copying occurs, the affected areas are then "infected," rendering your device "helpless" and "sick."
ILOVEYOU
This was perhaps the most dangerous computer virus ever created, in the form of a worm – a self-replicating program. Known as ILOVEYOU, this virus initially traveled the Internet via email and managed to crash computers all over the world. To make it even more enticing, the subject of the email was a love letter from a secret admirer. An attached file in the email was what caused all the trouble. The original worm had the file name LOVE-LETTER-FOR-YOU.TXT.vbs. The moment someone opened the file, the virus sent itself to the first 50 contacts available in the computer’s address book. The virus caused a total loss of $10 billion and affected almost 10% of the computers in the world.
Melissa
Melissa was the first mass-mailing macro virus in the new age of email that made headlines around the world on March 26, 1999. Based on the Microsoft Word macro, it was created by David L. Melissa spread in the form of an email attachment named “List.doc.” When someone clicked on it, the virus replicated itself and sought to be emailed to the first 50 names on the list with the message, “Here is the document you requested… don’t show it to anyone else. 😉” Later, the FBI arrested David L and fined him $5000 for releasing the fastest virus of its time.
My Doom
My Doom appeared on January 26, 2004, and shocked the world as it spread via email via random sender addresses and subject lines. My Doom devastated the cyber world by triggering a massive denial-of-service attack that infected an estimated two million computers. It was spread in a particularly deceptive manner via email, as it presented itself as an error message that read “Mail transaction failed.” But, once the message was opened, the attachment was executed and the worm was transferred to email addresses in the user’s address book. The damage caused by this fast-moving mailer worm was $38 billion.
Code Red
It debuted in late 2001 by exploiting a flaw in Microsoft Internet Information Server. Variants of the virus plagued the Internet for several months. The interesting thing about this deadly virus is that it didn’t require you to open an email attachment or execute a file, it only required an active Internet with which it would crash the website you opened by displaying a text “Hacked by the Chinese!” And in less than a week, “Code Red” brought down over 400,000 servers, including the one at the White House. This virus caused a total damage of about $2.6 billion dollars as it affected a million computers.
Sasser
The 2004 worm primarily affected Windows OS and was devastating to many critical infrastructures. It was not spread through email unlike other viruses. Instead, when the virus infected a computer, it searched for other vulnerable systems. It contacted those systems and instructed them to download the virus. The virus scanned random IP addresses to find potential victims. The virus also altered the victim's operating system in a way that made it even more difficult to restore without cutting off power. Sasser operated by an attacker in the Local Security Authority Subsystem Service, as it had a buffer overflow vulnerability. After one million attacks, the damage was estimated to be $18 billion.
