Security in OPERA Specification bad PLC Systemsxsysinfo
Guiomar Corral, Jop M. Selga, Agustín
Zaballos, David González-Tarragó
prentvalue
Enginyeria i Arquitectura La Salle-Universitat Ramon
Llull (URL)
Barcelona-Spain
{jmlga, guiomar, zaballos, dgonzalez}@salle.url.edu
Luis M. Torres
灵格斯翻译软件Design of Systems on Silicon (DS2) SA
Valencia, Spain
Berthold Haberler新手妈妈学婴语
Linz Strom Gmbh
Linz, Austria
Abstract— Power Line Communication (PLC) is a broadband telecommunication technology that enables the u of the existing electricity networks for high speed data transmission purpos. European project OPERA (Open PLC European Rearch Alliance) is a project who strategic objective is to push PLC technology in all the different and relevant aspects. Within this framework, curity is an important aspect thatshould be taken into account and integrated into thespecifications from the very beginning. The project was scheduled in two phas with a duration of two years each. Pha1 produced a first PLC specification, including curity.Pha2 produced an improved specification which was submitted to the IEEE as the OPERA PLC proposal within thecontest organized by WG P1901. The paper prents the studies related to curity in the PLC access technology made within this process that led to the cond curity specification of OPERA. Finally, an analysis of this specification isperformed.
Keywords- access technologies; PLC; communications network curity;
OPERA project.
I. INTRODUCTION
statistics
Power Line Communication (PLC) is a broadband telecommunication technology able to u the existing electricity networks for data transmission purpos, allowing any ur connected to the power grid to benefit from Information Technology bad rvices easily. The strategic objective of project OPERA (Open PLC European Rearch Alliance) [1] is to push PLC technology in all the different and relevant aspects (standardization, technology improvement, installation tools and process, telecom rvices, dismination,..) so as to allow the technology to become a competitive alternative to offer broadband access rvice to all European citizens using the most ubiquitous infrastructure, the electrical grid, which covers not only the last mile but also in-building and in-home spaces.
Security has been sometimes neglected when defining standards. In fact, the initial specifications of many existing standards in related areas such as wireless [2] have been shown to have many vulnerabilities that have had to be fixed
in further specifications, not without trouble for the market. Unfortunately OPERA is not different. The specification produced in OPERA Pha1 [1][3] prented also veral vulnerabilities that have been
chrismasfixed in OPERA Pha2 specification [4]. The writing of this cond specification by OPERA was inscribed in some way in the process created by the IEEE WG P1901 with the intention of producing an IEEE standard for PLC access and in-home networks. In fact, deliverable D27 [4] is the proposal submitted by OPERA to the IEEE within the mentioned process.
The prentation of the OPERA Pha2 specification and the related curity analysis are the objectives of this paper.
The contents of the prent paper is organized as follows. Section II introduces the curity requirements to be complied by the specification; Section III succinctly describes the OPERA Pha1 specification; Section IV analyzes the level of compliance of this specification; Section V outlines the basic ideas for
creating a new specification; Section VI contains a curity analysis of the new specification and, finally, there is a conclusions ction.
II. SECURITY REQUIREMENTS
The basic objectives of any curity specification are to achieve confidentiality, integrity, mutual authentication and availability. The objectives can be threatened by a ries of attacks.
Confidentiality is interpreted as the privacy of transactions between two nodes from all other nodes. It is made possible by the techniques of cryptography. The most relevant known attacks against confidentiality are [5]: brute force attack, dictionary attack, eavesdropping attack and precomputation attack.
Data integrity refers to ensuring that data has not been altered during the transmission process. Malicious manipulation and forging of messages are different attacks against data integrity. It can be prevented by the u of Message Integrity Checks (MIC).
The function of admission control is to guarantee that network resources are only accesd by authorized devices which are who claim to be. Thus, it contains two aspects, one is authentication of the stations and the other is authorization to access the resources. Normally both functions are combined in a single access protocol. Different attacks against admission control are the following: identity usurpation, replay attacks, man-in-the-middle attacks, hijack of MAC address, ssion hijacking, masquerading, malicious device and message interception. Availability refers to the prevention from accessing and using the network by some unauthorized party. Attacks to availability are called Denial of Service (DoS) attacks. The curity requirement demands that the specificationmust be robust against the attacks as well as to any other possible attack.
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III. SUCCINCT DESCRIPTION OF OPERA PHASE 1 SECURITY SPECIFICATION OPERA1 Specification [2][3] is aimed for PLC access networks and defines three types of devices, Head-End (HE), Repeaters (TDR, Time Division Repeaters) and Customer Premis Equipment (CPE). They typically form a
multi-hop system like the one depicted in Figure 1.
Confidentiality in OPERA1 is achieved by the u of DES[6] and 3DES[7] encryption systems. The admission control process involves three messages: an Access Frame that invites nodes to join the network, a contention Access Reply Frame that is an answer to the Access Frame and arequest to join the network and, finally, an Access Protocol Packet that basically informs about the success or failure of the admission control process. It is, thus, a 3-wayhandshake.
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The MAC layer is bad on token passing controlled by the HE. The HE organizes and controls the downlink data frame for all data transmission from the HE to the CPEs. It also assigns the access duration for each CPE, which allows the uplink transmissions from the CPEs to the HE [2][8].
The data frame structure ud in the uplink and downlink transmissions is illustrated in Figure 2 [8]. Each frame begins with a “token announce” (TA). The TA is broadcasted in the clear over the networ
k to inform the other stations about the upcoming transmission. The TA is followed by a number of bursts, each one addressing a specific CPE. Each burst consists of a burst header followed by veral OPERA packets (basically similar to Ethernet packets). An interpacket header is inrted to parate two continuous packets or fragments of packets in a burst. The last symbol of the data frame carries a “Data Token” (DT).justcar
IV. OPERA PHASE 1 SPECIFICATION SECURITY ANALYSIS
The most relevant vulnerabilities of OPERA Pha1 specification that have been detected are the following:
Vulnerability 1: It us DES [6] with a 56/64 bit key which has been reported to be breakable. It has even been phad out by FIPS (Federal Information Processing Standards). Brute force attacks as well as other attacks are feasible. Vulnerability 2: Admission control is only bad on MAC address. Since the address are necessarily nt in the clear over the PLC channel, they can be supplanted. Hijacking and identity usurpation are easy to deploy.danny brown
Vulnerability 3: There is no mutual authentication. There is no provision to authenticate masters. A malicious masterand man-in-the-middle attacks are possible.
Vulnerability 4: The OPERA1 proposal does not contain any curity Message Integrity Check (MIC) that could prerve data against tampering. Vulnerability 5: Channel Estimation MPDUs are never encrypted and include no MIC. Thus they can be manipulated to cau a DoS attack.
Vulnerability 6: Another possible data integrity attack is just to change the position of different blocks in the payload. This would be unnoticed due to the independent ciphering of each block. It is a permutation attack.
Vulnerability 7: It us Diffie-Hellman algorithm without any protection against Man-in-the Middle attack. Although this may em a big number of vulnerabilities of the OPERA Pha1 specification, the situation is common with other technologies, the most relevant of them being the early IEEE802.11 curity specification [1].
V. OUTLINE FOR A NEW OPERA SECURITY SPECIFICATION
Upon the view of the previous vulnerabilities it was clear that a new specification was needed and that it should provide stronger encryption,
