cyber attacks that paralyzed major South Korean and U.S. government Web sites

An updated version of the MyDoom virus is responsible for a large DDOS (distributed denial of service) attack that took down major U.S. Web sites over the weekend and South Korean Web sites on Wednesday, according to Korean computer security company AhnLab.

When it was discovered in January 2004, MyDoom quickly became the fastest-spreading e-mail worm in Internet history. Once a PC was infected with MyDoom, it would harvest e-mail addresses and e-mails itself out repeatedly. Early variants MyDoom were coded to conduct DDOS attacks against other Web sites within certain time periods.

The latest MyDoom variants seen by AhnLab also include a downloader that can bring other malicious code into the compromised PC, a feature also present in earlier versions of the malware. An additional file contains details of Web site to be attacked.

It lists 13 South Korean Web sites and 23 U.S. sites, according to a Korean blogger who analyzed the source code. Most of the sites on the list are those reported to have been attacked or are still under attack.

Source: yahoo news

So what is the so called DDOS?

A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts of a person or persons to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely. Perpetrators of DoS attacks typically target sites or services hosted on high-profile web servers such as banks, credit card payment gateways, and even root nameservers.

One common method of attack involves saturating the target (victim) machine with external communications requests, such that it cannot respond to legitimate traffic, or responds so slowly as to be rendered effectively unavailable. In general terms, DoS attacks are implemented by either forcing the targeted computer(s) to reset, or consuming its resources so that it can no longer provide its intended service or obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately.

Diassembled DDOS code

DDOS sampletools used by some unethical hackers..

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