NIPAD： a non-invasive power-based anomaly detection scheme for programmable logic controllers  

作　　者：Yu-jun XIAO Wen-yuan XU Zhen-hua JIA Zhuo-ran MA Dong-lian QI 

机构地区：[1]School of Electrical Engineering, Zhejiang University, Hangzhou 310027, China [2]Wireless Information Network Laboratory, Rutgers University, North Brunswick, NJ 08902, USA

出　　处：《Frontiers of Information Technology & Electronic Engineering》2017年第4期519-534,共16页信息与电子工程前沿（英文版）

基　　金：Project supported by the National Basic Research Program(973)of China(No.2015AA050202)

摘　　要：Industrial control systems （ICSs） are widely used in critical infrastructures, making them popular targets for attacks to cause catastrophic physical damage. As one of the most critical components in ICSs, the programmable logic controller （PLC） controls the actuators directly. A PLC executing a malicious program can cause significant property loss or even casualties. The number of attacks targeted at PLCs has increased noticeably over the last few years, exposing the vulnerability of the PLC and the importance of PLC protection. Unfortunately, PLCs cannot be protected by traditional intrusion detection systems or antivirus software. Thus, an effective method for PLC protection is yet to be designed. Motivated by these concerns, we propose a non-invasive power- based anomaly detection scheme for PLCs. The basic idea is to detect malicious software execution in a PLC through analyzing its power consumption, which is measured by inserting a shunt resistor in series with the CPU in a PLC while it is executing instructions. To analyze the power measurements, we extract a discriminative feature set from the power trace, and then train a long short-term memory （LSTM） neural network with the features of normal samples to predict the next time step of a normal sample. Finally, an abnormal sample is identified through comparing the predicted sample and the actual sample. The advantages of our method are that it requires no software modification on the original system and is able to detect unknown attacks effectively. The method is evaluated on a lab testbed, and for a trojan attack whose difference from the normal program is around 0.63%, the detection accuracy reaches 99.83%.工业控制系统广泛应用于关键基础设施的建设中,关系到国计民生,因此,攻击者越来越多地将其作为攻击目标,并造成严重的破坏。可编程逻辑控制器(Programmable logic controller,PLC)作为工业控制系统中的核心组件,能够直接控制现场设备,一旦PLC中运行了恶意程序,则可能直接造成重大财产损失甚至是人员伤亡。近些年来,针对PLC的攻击事件显著增加,这表明PLC存在很大的脆弱性,同时也提醒人们保护PLC安全的重要性。不幸的是,传统的入侵检测系统和杀毒软件并不能很好地保护PLC的安全,因此,针对PLC的有效的安全防护方案有待被研究。基于上述背景,本文提出了一种非侵入式的基于功耗的PLC异常检测方案。该方案通过分析PLC运行时的功耗变化来检测PLC中是否运行异常程序,分为功耗信息获取与功耗分析两部分。采集功耗信息是通过在PLC的供电线上串入一个电阻实现的,当PLC运行时,测量电阻两端的电压即可获取CPU的功耗信息。为了更好的分析功耗信息,本文首先从原始功耗数据中提取有效的特征值组合,然后利用正常样本来训练一个基于长短记忆(long short-term memory,LSTM)单元的神经网络模型,利用该模型对后续正常样本进行预测,通过比较测量到的功耗信息与预测的功耗信息,可以确定当前PLC中运行的程序是否为正常程序。该方案的优点是无需对原工控系统的封装部分进行软硬件的修改,且无需负样本即可实现对未知攻击的检测。我们在实验室测试平台上对该方法进行了评估,实验表明,对于原程序,只需改动0.63%即可达到99.83%的准确率。

关 键 词：Industrial control system Programmable logic controller Side-channel Anomaly detection Long short-term memory neural networks 

分 类 号：TP309.1[自动化与计算机技术—计算机系统结构]