Scanning the cycle : timing-based authentication on PLCs

Ahmed, Chuadhry Mujeeb and Ochoa, Martin and Zhou, Jianying and Mathur, Aditya; (2021) Scanning the cycle : timing-based authentication on PLCs. In: ASIA CCS 2021 - Proceedings of the 2021 ACM Asia Conference on Computer and Communications Security. ASIA CCS 2021 - Proceedings of the 2021 ACM Asia Conference on Computer and Communications Security . Association for Computing Machinery, Inc, HKG, pp. 886-900. ISBN 9781450382878 (https://doi.org/10.1145/3433210.3453102)

[thumbnail of Ahmed-etal-ASIACCS-2021-Scanning-the-cycletiming-based-authentication-on-PLCs]
Preview
 Text. Filename: Ahmed_etal_ASIACCS_2021_Scanning_the_cycletiming_based_authentication_on_PLCs.pdf
Accepted Author Manuscript
Download (10MB)| Preview

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.

CORE (COnnecting REpositories)