CS406: Information Security

Overview

• 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, motives for, and targets of a DoS attack may vary, it generally consists of the concerted, malevolent efforts of a person or persons to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely.
• The purpose of DoS attacks is to force the targeted computer(s) to reset, or consume its resources so that it can no longer provide its intended service.
  
  

Types of DoS Attacks

A DoS attack can be perpetrated in a number of ways. There are five basic types of attack:

• Consumption of computational resources, such as bandwidth, disk space, or CPU time
• Disruption of configuration information, such as routing information
• Disruption of state information, such as unsolicited resetting of TCP sessions
• Disruption of physical network components
• Obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately

Countermeasures

Unfortunately, there are no effective ways to prevent being the victim of a DoS or DDoS attack, but there are steps you can take to reduce the likelihood that an attacker will use your computer to attack other computers:

• Install and maintain anti-virus software.
• Install a firewall, and configure it to restrict traffic coming into and leaving your computer.
• Follow good security practices for distributing your email address. Applying email filters may help you manage unwanted traffic.