Denial of Service Attacks
also known as DNS or DOS Attacks
 - including SYN flooding
this page last updated 2002 Oct 23, 2006 Nov 16
- see also the page on 
 www.witiger.com/ecommerce/hackers.htm
This page is prepared by Prof. Tim Richardson for his students.
The purpose is to put all the basic info together in one place about Denial of Service Attacks.
This is not intended to be an exhaustive treatment of the subject
- but rather a collection which would serve the purposes of students taught by "witiger".
 
Denial
of
Service		 Denial of Service 

Sometimes abbreviated as DNS attacks, sometimes as DoS

"DoS attacks are relatively  simple to perform but can have  devastating effects. They  disable Web sites and routers  by flooding them with false  information requests. In order to discover the source of the requests, technicians must sort through thousands of lines of computer code. DoS attacks can last hours or  days, depending on how quickly they are detected."
Tim McDonald
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Denial
of
Service

BASICs
"A Denial of Service Attack is used to destroy, shut down, or degrade a computer  or network resource. The goal of the attack is to flood the communication ports and memory buffers of the targeted site to prevent the receipt of legitimate messages and the service of legitimate requests for connections. These types of attacks are on the rise as methods and program code for conducting such acts are publicly available on hacker websites".

in Greenstein's book Electronic Commerce Security, 2nd ed.
Chpt 7 Risks of Insecure Systems,  p. 224
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Denial
of
Service
"Denial of service attacks have been called the ultimate Internet Security nemesis."

"DOS attacks are aimed solely at making service unavailable. The attacks are particularly difficult to defend against, because they exploit structural weakness or flaws in widely used protocols"

in Ghosh's book E-Commerce Security, page 20, Chpt 1
 
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Denial
of
Service
Attacks
Reported
in the
Online
Media		 Denial of Service Attacks

First became known in the general public in February 2000 when several large sites were crippled, some of them for several hours.
 

BusinessWeek article interviewing Bruce Schneier about "distributed denial-of-service attacks"
 www.businessweek.com/2000/00_10/b3671089.htm.
" The nature of distance has also changed. In the world offline, your house only has to be secure from criminals within driving distance. On the Net, eBay (EBAY) and Yahoo! (YAHOO) must be concerned about everyone on the planet. The hackers  need not be in America. This is the death of distance: Crime is no longer based on proximity."
 
KEY
POINTS		 One of the things that challenges security experts like Schneier, is the fact that such crimes can by launched by people with no close proximity to the target. In a traditional security and risk situation, at some time, for the threat to be "launched", there has to be some resources brought within striking distance of the target - in the case of DOS, it can be done with relatively small resources halfway around the world..
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"We are dealing with fact that software products are always buggy, and probably always will be. At the same time, systems are too complex to secure. We actually can't test security to the level we need to. We'll see three or four major bugs in each new version of Windows or Explorer or Java. New products are coming out faster and faster, so we keep losing ground. We've been finding and fixing security bugs in past years, but none of those fixes transfers forward. For all these programs, a new version comes out, the new version is more complex, and there are new bugs."

Q: BusinessWeek - Is there any defense against distributed denial-of-service attacks?
A: Schneier, - "We don't really know how to defend against this kind of thing. All the defenses
I've heard of are of the civic hygiene variety--in other words, making sure all computers on the Net are secure. But that isn't possible, technically. Even if you put firewalls around 99.99% of computers--which is very unlikely--malicious programs would sniff out the remainder that weren't secured".
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http://www.cert.org/tech_tips/denial_of_service.html
 www.cert.org/tech_tips/denial_of_service.html
CERT is based at Carnegie Mellon University		 CERT publishes a number of authoritative documents on computer security.

"A recent report from the CERT Internet security center at Carnegie Mellon University  indicated that denial of service
 attacks are getting easier to  create and are having greater
 impact. "
 
The CERT  Coordination Center is part of the Software Engineering Institute. The Software Engineering Institute is operated by Carnegie Mellon University for the Department of Defense.
.
http://www.cert.org/archive/pdf/DoS_trends.pdf In the context of Denial of Service Attacks, CERT produced a paper in October 2001 which covers issues on the topic
 www.cert.org/archive
/pdf/DoS_trends.pdf

The CERT paper on DNS was produced by Kevin Houle and George Weaver
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Denial
of
Service
Attacks
Reported
in the
Online
Media		 Denial of Service Attacks
 
E-commerce Times reported on Denial of Service Attacks in February 2000 and a year later ran some stories on how this new threat was significant at the time.
By Tim McDonald, writing for the site  www.NewsFactor.com, produced and article February 6, 2001 titled
"Companies Race To Solve Denial-of-Service Riddle" 
which was carried in E-Commerce Times