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ISO/IEC 27039
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Copyright © 2016 IsecT Ltd.

ISO/IEC 27039:2015 — Information technology — Security techniques — Selection, deployment and operation of intrusion detection and prevention systems (IDPS)


IDS (Intrusion Detection Systems) are largely automated systems for identifying attacks on and intrusions into a network or system by hackers and raising the alarm. IPS (Intrusion Prevention Systems) take the automation a step further by automatically responding to certain types of identified attack, for example by closing off specific network ports through a firewall to block identified hacker traffic. IDPS refers to either type.

Scope and purpose

The scope states “This International Standard provides guidelines to assist organizations in preparing to deploy Intrusion Detection Prevention System (IDPS). In particular, it addresses the selection, deployment and operations of IDPS. It also provides background information from which these guidelines are derived.”

Well designed, deployed, configured, managed and operated IDPS are valuable in several respects, for example:

  • Automation leverages scarce security engineers who would otherwise have to monitor, analyze and respond to network security incidents as best they could;
  • Automation tends to speed-up identification and response to attacks, particularly common types of attack that can be identified unambiguously through unique attack signatures;
  • They give additional assurance to management that security issues on the networks and networked systems are being identified and mitigated.

The standard is, in effect, an ISPS implementation guide and advisory.


Three main sections comprise the bulk of the standard’s ~50 pages:

  • Selection of IDPS - various IDPS types, complementary tools etc. to consider (in some detail, expanded still further in the annex);
  • Deployment of IDPS;
  • IDPS operations.

Status of the standard

The standard was published in 2015, “revising and canceling” (i.e. replacing) ISO/IEC 18043:2006.

A technical corrigendum published on May 1st 2016 corrected the title of the published standard, reintroducing the conspicuously absent words “and prevention” that somehow got lost along the way.

Personal comments

I had hoped the standard would mention, in addition to the network security risks that they are meant to address, various information risks and issues associated with or introduced by the IDPS themselves, such as:

  • They are technologically advanced and complex, making them difficult to configure, deploy and use effectively, hence there is a risk that they may be incorrectly configured, deployed or used in practice, with various consequences on the organization and other systems. Furthermore, they probably introduce additional technical security vulnerabilities into the very networks and/or systems they are supposed to protect;
  • They may adversely affect network traffic, restricting legitimate traffic and hence normal use of the network and systems, as well as hacking traffic;
  • They are not 100% capable, meaning that certain types or modes of attack (particularly novel ones) may not be reliably identified and hence blocked, potentially creating a false sense of security (inappropriate assurance);
  • They can only detect and react to available information, making them blind and deaf to attacks that bypass the networks and systems being monitored (including, for examples, social engineering and physical intrusion attacks);
  • They usually require network bandwidth, processing and storage capacity for their own operations and record-keeping, and require hooks into the networks and systems being monitored and/or controlled, impinging upon normal use;
  • They are complicated to configure and manage for best effect, requiring the involvement of competent security engineers who, potentially at least, may themselves be hackers;
  • They require privileged access to network traffic, network devices and/or systems, and could potentially be misused as a vector or mechanism to compromise them.

However, it does not ...