Denial of Service Handling

Definitions

Denial of Service Handling

the security quality subfactor representing the degree to which decreased performance and/or operational availability caused by denial of service (DoS) attacks is properly handled

Objectives

The typical objectives of denial of service handling are to:

• Ensure that security properly addresses the malicious harm that can be caused by denial of service (DoS) attacks
• Model the degree to which decreased performance and/or operational availability caused by DoS attacks is:
  • Prevented
  • Detected
  • Reacted to
  • Adapted to
• Support the analysis and specification of denial of service handling requirements

Measures

Denial of service handling is typically measured in terms of:

• Maximum/average actual/percentage decrease in performance per DoS attack
• Maximum/average actual/percentage decrease in operational availability per DoS attack
• Maximum/average downtime per DoS attack
• Percentage of DoS attacks detected
• Percentage of DoS attacks responed to in a specific manner (e.g., failover, notification of security engineer)

Mechanisms

Typical mechanisms for improving denial of service handling include:

• Deny access to services by unauthorized users.
• Use multiple URLs in case a denial of service attack causes excessive service requests do a single server.
• Use a laser instead of radio for wireless communication to limit the possibility of jamming.

Guidelines

The following guidelines have been found to be useful regarding denial of service handling:

• Denial of service handling is typically called availability in the security community. However, denial of service handling is quite different from the traditional operational availability quality factor. Operational availability does not address performance and only applies when the application or component is not under attack.
• Denial of service protection deals with the following security concepts:
  
  

  Security Concept	Value
  Valuable Asset	Some service
  Malicious Harm	Denial of that service by an attacker
  Security Incident	Denial of Service Attack
  Threat	Existence of attacker(s) with means and motive to cause denial of service attacks
  Security Risk	Can be low or high depending on the number of motivated attackers, their profiles, appropriate security countermeasures, and vulnerabilities that can be exploited by attacks