Indicators of Compromise (IoCs) and Their Role in Attack Defence

draft-paine-smart-indicators-of-compromise-01

Internet Engineering Task Force K. Paine Internet-Draft UK National Cyber Security Centre Intended status: Informational O. Whitehouse Expires: January 14, 2021 NCC Group July 13, 2020 Indicators of Compromise (IoCs) and Their Role in Attack Defence draft-paine-smart-indicators-of-compromise-01 Abstract Indicators of Compromise (IoCs) are an important technique in attack defence (often called cyber defence). This document outlines the different types of IoC, their associated benefits and limitations, and discusses their effective use. It also contextualises the role of IoCs in defending against attacks through describing a recent case study. This draft does not pre-suppose where IoCs can be found or should be detected - as they can be discovered and deployed in networks, endpoints or elsewhere - rather, engineers should be aware that they need to be detectable (either by endpoints, security appliances or network-based defences, or ideally all) to be effective. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on January 14, 2021. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents Paine & Whitehouse Expires January 14, 2021 [Page 1] Internet-Draft Indicators of Compromise July 2020 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may not be modified, and derivative works of it may not be created, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. What are IoCs? . . . . . . . . . . . . . . . . . . . . . . . 3 4. Why use IoCs? . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. IoCs can be used even with limited resource . . . . . . . 4 4.2. IoCs have a multiplier effect on attack defence effort . 5 4.3. IoCs are easily shareable . . . . . . . . . . . . . . . . 5 4.4. IoCs can be attributed to specific threat actors . . . . 5 4.5. IoCs can provide significant time savings . . . . . . . . 6 4.6. IoCs allow for discovery of historic attacks . . . . . . 6 4.7. IoCs underpin and enable multiple layers of the modern defence-in-depth strategy . . . . . . . . . . . . . . . . 6 5. Pain, Fragility and Precision . . . . . . . . . . . . . . . . 7 5.1. Pyramid of Pain . . . . . . . . . . . . . . . . . . . . . 7 5.2. Fragility . . . . . . . . . . . . . . . . . . . . . . . . 9 5.3. Precision . . . . . . . . . . . . . . . . . . . . . . . . 9 5.4. Comprehensive Coverage . . . . . . . . . . . . . . . . . 9 6. Defence in Depth . . . . . . . . . . . . . . . . . . . . . . 10 7. Case Study: APT33 . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Overall TTP . . . . . . . . . . . . . . . . . . . . . . . 12 7.2. IoCs . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 13 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 11. Security Considerations . . . . . . . . . . . . . . . . . . . 14 12. Informative References . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16