> Denial of Service by Darren Pierce <
Last Updated : 15:15:28 on 20 April, 2000 


I. What is Denial of Service?

Denial of Service (DoS) is a technique used to attack a system and crash it. This can be both remotely or on site and both can be very consequential to the victim's machine. Like the name suggests, when a system is hit with a successful Denial of Service attack, their machine is usually rendered inoperable for a period of time and is denied the service it was either offering or using.


II. How do you perform a Denial of Service attack?

This isn't going to be covered in great detail as this isn't meant to be a tutorial on fucking up machines. Denial of Service attacks, as previously mentioned, are performed either remotely or on site to the machine. Most DoS attacks are performed remotely and exploit an error in a program running on the victim machine, which can cause a computer to freeze up and crash, or even open a backdoor in the system.


III. Why would someone want to perform a Denial of Service attack?


A. The Influence of the underground culture.

The underground culture has a lot to do with why people perform Denial of Service attacks. There are many individuals who fall into a category of young people who enjoy going around, attacking innocent people for no real reason, and gloating about how they are "hackers". These people are known as Script Kiddies and make up a significant part of the internet community, as well as 90% of the America Online community. These people are influenced by the underground community and try to achieve the glamour that is associated with being a hacker. The only problem is, these netizens are young, and are influenced by the dark side, so to speak. They get involved with other people that associate the Denial of Service attacks with being a hacker, and follow the same path. They perform Denial of Service attacks on any and everyone that is susceptible to the attacks. Most script kiddies hang out in chat rooms and gloat about how many people they have "owned" or successfully attacked. Usually script kiddies evolve and become a useful entity, but until they do, they are nothing more than kids with guns and contribute nothing to the community.


B. Research and Security Improvement.

The other side of the coin would be people who hunt for Denial of Service attacks to better improve the performance as well as the security of computer systems. These people are the ones who discover the attacks that the script kiddies so often use. Although they are to blame for the arsenal that the script kiddies possess, they cannot be held accountable. Their actions are noble, these people are the true hackers and their motives are simple; the advancement of computer security. One such group that researches security holes and possible Denial of Service attacks would be The L0pht.


IV. What does someone have to gain from Denial of Service attacks?


A. Access to a Machine.

One of the main objectives of Denial of Service attacks is to gain unauthorized access to a machine. Many DoS attacks are launched against security programs that once crashed, leave the system open for intruders. Denial of Service attacks can also be launched as a diversion for an unauthorized access to a system. While a system administrator is busy attempting to get the web server back on the internet, someone could be compromising the security of the unmanned email server, the possibilities are endless.


B. Political and Economic Motives.

Like most things in life, computers can be pawns in a political strategy. Instead of wars with guns, tanks and bombs, governments could (if they already don't) wage a political war over the internet. With the amount of trust placed on technology and computers, and the amount of things that they control, it would be very feasible to launch a massive Denial of Service attack against another government's servers in hopes of ceasing the flow of voice and data transmissions. Even launch an attack to cause a diversion while hi-jacking top secret plans for a new piece of machinery, or just plant a simple key logger into a system to obtain sensitive data as it is being entered. In fact, no one would be safe from a full-scale political war with computer. Power being cut off for an entire country because of an attack could cause a great deal of problems for a country.

There are no full-scale internet wars as of yet, but there are many low fidelity attacks against political web sites as a protest against the government they represent. This happens in many countries that have strict internet laws, and the citizens (well the hackers in the community) feel it is a great injustice. They protest by taking down a server and then contacting a local news source and taking credit for the attack and give their reasons for doing so. In most cases this exposes the truth and could potentially cause the government to change their policies because of the fear of a citizen uprising.

Economic motives can also be a serious factor. Web sites that are in the same market that are competing could launch Denial of Service attacks against each other in hopes of knocking their competitor out of the race and leaving the other to snatch up all the business. I'm not too sure how often this happens, if it even happens at all. There is a lot of dirty activity going on amongst businesses, so if it hasn't happened yet, it eventually will.


C. Protest.

Many systems connected to the internet are attacked in protest. Protesting everything from business ethics to someone just not liking a product. These protests are usually somewhat meaningless, but occasionally they have a good reason. Most of the time though, sites are simply defaced as opposed to being denied service for protest. But as of late, there seems to be more of a turn toward Denial of Service attacks as opposed to site defacements; as a method of protest.


D. Revenge.

Like anything else destructive in nature. Denial of Service attacks can be used as a way to get revenge on another person, government or corporation. The revenge aspect seems to fall more into the script kiddies domain. One kid attacks another kid. The other kid tells his friends and they attack the original attacker. The original attack gets his friends and attacks the original victim's friends, and so on until it gets so confusing that no one knows why they are attacking each other. Another example would be a user being ripped off by a site that sells goods. As a revenge tactic, the person who was ripped off could launch a Denial of Service attack against the companies web server. This may not get the person anywhere, but more than likely it will give then a sense of closure.


E. Just Because.

The last reason for Denial of Service attacks would be "just because". Many people attack other people just because they are there, and just because they can. For the most part, these people make up the majority of the script kiddie sub-species of netizen. In most cases, the script kiddies chat on Internet Relay Chat (IRC) and whenever someone stumbles in their channel and isn't as "elite" as they are, they would attack the unsuspecting victim. This occurs on most chat mediums (IRC, ICQ, AOL Chat Rooms, Yahoo! Chat, et cetera) and is the equivalent of shooting fish in a barrel. 


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