Denial of service (DoS) attack: An incident in which a user or organization is deprived of the services of a resource they would normally expect to have. DoS attacks can occur in many different ways.
The five most common are:
1. Consumption of computational resources: This can include consumption of disk space, increase of processor usage, or consumption of bandwidth.
2. Changing configuration settings so that connections to servers or the internet is rendered impossible.
3. Resetting certain services so that connection to other computers or the internet is difficult or impossible.
4. Disabling hardware devices so that connections cannot be made.
5. Overloading communication devices to the point where no communication is possible due to too much demand.
The effects of a DoS attack are many and will vary depending on the effect desired.
Common effects may include:
Causing the system to consume resources to the point where no real work can be done.
Creating glitches in the core of the machine, causing instability of the operating system.
Mangling the sequence of instructions so as to cause the system to become unstable or lock up.
Crashing the operating system.
Distributed denial of service attack (DDoS): The use of multiple infected computer systems to perform a much stronger DoS attack. A DDoS attack usually is started by infecting computers with a Trojan horse programs. This turns the infected computers into zombies which can then be remotely controlled and used to cause a DoS attack.
The main advantage of using a DDoS attack is that the attacker has more machines with which to attack the victims computer. It can also make it more difficult for the victim to combat the attack, as each machine can attack in stealthier methods, making it harder to track down and terminate the attack.
For example, if the attack plan was to consume bandwidth, purchasing more bandwidth volume would not work as the attacker could easily add more computers to their attack and consume the extra bandwidth purchased.
Tags: Denial of service