Scanning the cycle: timing-based authentication on PLCs

Chuadhry Mujeeb Ahmed, Martin Ochoa, Jianying Zhou, Aditya Mathur

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

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Abstract

Programmable Logic Controllers (PLCs) are a core component of an Industrial Control System (ICS). However, if a PLC is compromised or the commands sent across a network from the PLCs are spoofed, consequences could be catastrophic. In this work, a novel technique to authenticate PLCs is proposed that aims at raising the bar against powerful attackers while being compatible with real-time systems. The proposed technique captures timing information for each controller in a non-invasive manner. It is argued that Scan Cycle is a unique feature of a PLC that can be approximated passively by observing network traffic. An attacker that spoofs commands issued by the PLCs would deviate from such fingerprints. To detect replay attacks a PLC Watermarking technique is proposed. PLC Watermarking models the relation between the scan cycle and the control logic by modeling the input/output as a function of request/response messages of a PLC. The proposed technique is validated on an operational water treatment plant (SWaT) and smart grid (EPIC) testbeds. Results from experiments indicate that PLCs can be distinguished based on their scan cycle timing characteristics.

Original languageEnglish
Title of host publicationASIA CCS 2021 - Proceedings of the 2021 ACM Asia Conference on Computer and Communications Security
Place of PublicationNew York
Pages886-900
Number of pages15
ISBN (Electronic)9781450382878
DOIs
Publication statusPublished - 11 Jun 2021
Event16th ACM Asia Conference on Computer and Communications Security, ASIA CCS 2021 - Virtual, Online, Hong Kong
Duration: 7 Jun 202111 Jun 2021

Publication series

NameASIA CCS 2021 - Proceedings of the 2021 ACM Asia Conference on Computer and Communications Security

Conference

Conference16th ACM Asia Conference on Computer and Communications Security, ASIA CCS 2021
Country/TerritoryHong Kong
CityVirtual, Online
Period7/06/2111/06/21

Keywords

  • authentication
  • ICS security
  • PLC security
  • programmable logic controllers
  • SCADA security
  • scan cycle
  • timing channel

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