10 destructive computer viruses

It was only stopped from spreading after about a month. For tips on eradicating mass mailing viruses, read Email Scanners — Protection from viruses and malware. Computer users were still recovering from the damage caused by Blaster in when another mass-mailer known as Sobig.

F attacked. This computer virus caused billions of dollars in damage by stalling or completely crashing Internet gateways and email servers, resulting in the merciless slowing down of global Internet access. It harvested email addresses from various documents found in the infected computers.

The virus then sent itself to these addresses. It was able to send over a million copies of itself within just a few hours of the outbreak. By September of , it had deactivated itself, having been programmed to do so. It then ceased to be a threat. The virus was written by a Filipino programmer who was still a college student at that time.

The Conficker worm was released in , infecting millions of computers around the world. Once a computer was infected, this worm downloaded and installed malware from sites controlled by the hackers, including things like keystroke loggers and remote PC-control software. Hacked by Chinese! After about two weeks of infection, the virus was programmed to launch DDoS Distributed Denial of Service attacks on certain websites, including the server of the White House.

Released in , the Melissa virus was another mass-mailing malware that was said to have infected up to 20 percent of computers worldwide. This included the networks of Microsoft, Intel, and other companies that relied on MS Outlook as their email client.

Email servers around the world were forced to shut down in order to prevent the virus from spreading, as well as to remove the virus from their system. The virus came through email including an MS Word attachment. When opened, it emailed itself to the first 50 people in the MS Outlook contact list.

SQL Slammer is the least damaging virus in this list. MyDoom spread faster than any worm seen prior. If earlier worms, like Code Red see below , were about mischief, Fizzer was all about money.

Slammer works by releasing a deluge of network packets, units of data transmitted over the Internet, bringing the Internet on many servers to a near screeching halt. Through a classic denial of service attack, Slammer had a quite real effect on key services. But when it swept across computers worldwide in , it caught security experts off guard by exploiting a flaw in Microsoft Internet Information Server.

That allowed the worm to deface and take down some websites. Perhaps most memorably, Code Red successfully brought down the whitehouse.

It only took hours for Love Letter to become a global pandemic, in part because it played on a fundamental human emotion: the desire to be loved. It focused on money making schemes. Specifically the infected computers would begin to send out large amounts of pharmacy related spam or even porn-related products. This was an internet worm with a knack for spreading at breathtaking speed. It would cause a lot of havoc for public workers, the general public and businesses. The preferred modus operandi was the release of many network packets hence slowing down the internet to ridiculous levels.

The malware had been developed on the back of some major design flaws in the Microsoft Internet Information Server. Hence Code Red could effectively deface and even take down a number of websites. The malware would overwrite all sorts of image files.