Page 142 - DCAP516_COMPUTER_SECURITY

Computer Security

Notes Then, there can be threatening e-mails. E-mail is a useful tool for anonymously threatening
anybody on the Internet. It is very easy for anyone with even a basic knowledge of
computers to become a blackmailer by threatening someone via e-mail. Through e-mails,
cyber defamation is also possible. This occurs when defamation takes place with the help
of computers and/or the Internet. For example, someone publishes defamatory matter
about someone on a website or sends e-mails containing defamatory information to that
person’s friends or colleagues.
12. Denial of Service Tools: Denial of service attacks are usually launched to make a particular
service unavailable to someone who is authorized to use it. These attacks may be launched
using one single computer or many computers across the world. In the latter case, the
attack is known as a distributed denial of service attack. Usually, these attacks do not
require the access into anyone’s system.
These attacks are getting more popular as more and more cyber criminals realize the
amount and magnitude of loss, which can be caused through them. Usually, the attack is
initiated by sending excessive demands to the victim’s computer(s), exceeding the limit
that the victim’s servers can support and making the servers crash. Sometimes, many
computers are entrenched in this process by installing a Trojan on them; taking control of
them and then sending numerous demands to the targeted computer.
On the other side, the victim of such an attack may see many such demands (sometimes
even numbering tens of thousands) coming from computers from around the world.
Unfortunately, to be able to gain control over a malicious denial-of-service attack would
require tracing all the computers involved in the attack and then informing the owners of
those systems about the attack. The compromised system would need to be shut down and
then cleaned. This process may prove very difficult to achieve across national and later,
organizational borders. Even when the source(s) of the attack are traced there are many
problems. The victim will need to inform all the involved organisations in control of the
attacking computers and ask them to either clean the systems or shut them down. Across
international boundaries this may prove to be a difficult task. The staff of the organization
may not understand the language. They may not be present if the attack were to be
launched during the night or during weekends. The computers that may have to be shut
down may be vital for their processes and the staff may not have the authority to shut
them down. The staff may not understand the attack, system administration, network
topology, or any number of things that may delay or halt shutting down the attacking
computer(s).

If there are hundreds or even thousands of computers on the attack, with problems like the
ones mentioned above, the victim may not be able to stop the attack for days, by which
time the damage would have been done.
It is very simple for anyone to launch an attack because denial-of-service tools can easily
be procured from the Net. The major versions of distributed denial-of-service attack tools
are Trinoo (or trin00), TFN, TFN2K and Stacheldraht.
Denial-of-Service tools allow the attackers to automate and preset the times and frequencies
of such attacks so that the attack is launched and then stopped to be launched once again
later. This makes it very difficult to trace the source of the attack.
These tools also provide another service by which the attacking computer can change its
source address randomly, thereby making it seem as if the attack is originating from
many thousands of computers while in reality there may be only a few.

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