Unified Architecture for LargeScale Attested Metering

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Unified Architecture for Large-Scale Attested
Metering
Michael LeMay George Gross Carl Gunter Sanjam Garg
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Outline

• Introduction
• Advanced Metering Overview
• Threat Model
• Security Architecture
• Application to Threat Model
• Future Work

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Introduction

• Problem Advanced Meters exhibit a number of
  security and privacy vulnerabilities
• Project Objective Create a secure, private, and
  extensible architecture for future advanced
  meters
• Approach Attested Metering Apply Trusted
  Computing (TC) and virtualization technology to
  secure Advanced Metering network communications
  and computation

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Advanced Metering Infrastructure (AMI)

• Advanced Meters Electronic utility meters with
  bidirectional network connections to the Meter
  Data Management Agency (MDMA)
• Network types
• RF wireless (ZigBee/802.15.4, Wi-Fi/802.11,
  proprietary)
• Power-Line Communication (PLC)
• Broadband over PowerLines (BPL)
• Cellular (CDMA, GSM)
• Phone line
• Benefits
• Customer control
• Demand response
• Improved reliability

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Advanced Meter Functions

• Read data such as kWh consumption
• Disconnect/reconnect power remotely
• Request demand response from premise
• Execute diagnostics
• Reset meter (change season mode)
• Set date/time
• Clear tables
• Log in (username/password)
• Log out

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Metering Interactions
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Partial threat model

• Unethical customer
• May attempt to modify metering messages to steal
  service
• Has legitimate physical access to meter, could
  modify it
• Overly-intrusive MDMA
• Could use high-resolution metering data to
  determine behavior of metered residents
• Publicity seeker
• Cracker or virus author seeking physical
  disruption to garner publicity

Hart, 1989 Residential energy monitoring and
computerized surveillance via utility power flows
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Security Architecture Layers
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Security Architecture

• Use hypervisor on embedded processor to isolate
  metering applications
• Control network communications to external
  entities to prevent undesirable data leakage
• Use remote attestation to guarantee integrity of
  system components and individual VMs

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Approach Unethical Customer

• Review
• May attempt to modify metering messages to steal
  service
• Has legitimate physical access to meter, could
  modify it
• Remote attestation with virtualization verified
  by MDMA to ensure software was not tampered
• Physical tampering important (and very common)
  but mostly outside our scope
• Sometimes detectable if customer cuts connection
  to meter, causing outage notification to be
  transmitted

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Approach Intrusive MDMA
Measurement
What software are you running?
0x5413bcd731a4,0x8baaaf53,
Certify the software and TPM.
0x5413bcd731a4
OK, I trust you to calculate the bill.
Measurement
Measurement
Measurement
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Approach Intrusive MDMA

• Review
• Could use high-resolution metering data to
  determine behavior of metered residents
• Network monitor and irrevocable auditing notify
  customer of MDMA actions
• Remote attestation permits MDMA to confidently
  perform billing computations locally on meter

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Metering Workflows
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Virus/Worm Attack
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Virus/Worm Attack
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Publicity seekers

• Review
• Cracker or virus author seeking physical
  disruption to garner publicity
• Application isolation prevents compromised
  applications from affecting other parts of the
  meter.

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Future Work

• Address issues surrounding software distribution,
  updates, and removal
• Port to embedded architecture such as ARM or
  Atmel AVR, or other microcontroller used in
  modern meters
• Define and address key management issues
• Explore security-critical value-added
  applications for advanced meters, such as
  emergency network retasking

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Questions?

• Website
• http//seclab.uiuc.edu/attested-meter
• Michael LeMay
• mdlemay2_at_cs.uiuc.edu
• George Gross
• gross_at_uiuc.edu
• Carl A. Gunter
• cgunter_at_cs.uiuc.edu

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Appendices
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AMI (cont.)

• Standards
• ANSI C12.19
• Specifies how data is laid out in a meter, in
  terms of predefined tables
• Meter functions invoked by writing to special
  table and reading results from other tables
• ANSI C12.18
• Specifies how C12.19 tables are accessed using an
  optical port (or RS-232 in rare cases)
• ANSI C12.22
• Similar to C12.18, but works with any network

C12.18 port
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Virtualization

• Hypervisors, or Virtual Machine Monitors (VMMs),
  run entire guest operating systems in isolated
  system partitions
• Provide strong isolation between guests to
  prevent software by one vendor from interfering
  with software by another vendor

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Trusted Computing Problem

• Software is controlled by machine operator
• Machine operator, software distributor, or
  attacker can maliciously subvert software
• Modify binary
• Run on untrusted hardware
• Attach debugger to monitor operation
• Software publisher has no assurance that software
  is being used in unmodified state, as intended

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Remote Attestation

• Uses keys and Platform Configuration Registers
  (PCRs) embedded in Trusted Platform Module (TPM)
  to attest to integrity of system configuration
• Possible assurances
• System running trusted software
• System equipped with valid TPM
• Applications can also attest to the states of
  specific data files

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Approach Curious Eavesdropper

• Review
• Someone casually spying on neighbor
• Probably wouldnt go beyond scripted attack tools
• Use network technologies that support per-link
  encryption, not network-wide shared keys
• If necessary, use cryptographic tunnels

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Approach Motivated Eavesdropper

• Review
• Thief, criminal seeking intelligence on victims
• May be willing to physically modify hardware
• Soft attacks addressed by strong encryption.
• Physical attacks important but outside our scope

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Approach Active Attacker

• Review
• Wants to destabilize grid or cause blackout
• Could perform DoS to block demand reduction
  signals
• Could directly attack remote disconnect function
  on many meters to disconnect homes and businesses
• Properly authenticate and authorize MDMA,
  customer, and any other entities with access to
  control functions on meters.

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Prototype Hardware

• Hardware
• Dell laptop with TPM and USB ZigBee interface
  emulating meter
• RS-232 connected ammeter
• USB-connected UPS emulating battery backup,
  outage detection, and frequency measurement
• X10 home automation devices
• Desktop PC with RS-232 ZigBee interface emulating
  customer PC or MDMA

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Prototype HW Overview
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Prototype Hardware
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Prototype Software

• Java implementation of ANSI C12.19 with C12.22
• Xen Virtual Machine Monitor
• Linux Integrity Management Architecture (IBM)
• TrouSerS IBM Linux TCG Software Stack
• jTSS Java wrapper for TrouSerS

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Prototype Applications

• Consumer portal
• Provides realtime data about energy usage, demand
  response actions, and audit logs to customer
• Allows customer to
• Verify operation of external network filter
• Monitor transmissions from VMs
• Check audit logs for administrative actions
  performed on meter

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Prototype Applications (cont.)

• Meter Data Management VM
• Provides billing data, outage restoration
  notifications, and maintenance information to
  MDMA
• Accepts price schedules from MDMA
• Demand Response VM
• Processes direct Demand Response (DR) requests
  from MDMA VM
• Enacts customer DR preferences based on price
  signals received from MDMA VM

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How can you help us?

• Please give us feedback!
• Visit our website for more information
  http//seclab.uiuc.edu/attested-meter
• We welcome donations of metering hardware and
  software
• Helps us to understand capabilities of practical
  devices
• Directs our research to help solve actual
  problems in real devices