Securing Internet of Things with Trustworthy Computing

Demo: Securing IoT with Trustworthy Computing

l

© 2015 Trusted Computing Group 1


Agenda

• Introduction, problem statement and use case• Description of the Demo• Demo


Introduction, problem statement and use case


Introduction• This demo is a proof of concept• As a proof of concept, please let us know what you

think of what you see

Problem Statement• Can we implement strong authentication between all

equipment in a network, not just of one endpoint to another?

• By definition, single factor authentication is weak, two or more factors of authentication is strong


Demo Use Case• General Use Case:

– A deployment of IoT devices (sensors and actuators)– Central management for the IoT deployment is remote to the IoT

devices, over an Internet– Can we show that all equipment in the use case is owned by the

customer and that the software on that equipment has not been changed?

• Specific example: Smart buildings– A smart building in Manhattan may have thousands of devices like

cameras, thermostats, HVAC actuators, etc.– Central management for the building might be in a datacenter in Dallas.– What can be done to enhance the security and trustworthiness of all of

the devices, including network gear, in this example?


Description of the Demo


What the Demo Shows• Strong authentication in Machine to Machine

(M2M) communications– Uses certificate and integrity validation

• M2M authentication is point to point across a network, including auth of routers to end points– No implicit trust is required in this demo

• Authentication is policy-based, locally enforced

The Demo Equipment & LayoutRaspberry Pi Cisco CGR 1120

Cisco UCS 240 Server

Our IoT deployment Our network gear

Our management server

Stacy Cannady


Authentication Flow Between rPi and CGR

Raspberry PiCisco CGR 1120

1. Start Session? 2. Who are you? Can I trust you?

3. Here are my identity and TPM-signed integrity

information 4. Verify identity and

integrity (done locally)

6. Open SSL session to Server through CGR 5. Session authorized


Authentication Flow Between Server and CGR

1. Start Session?2. Who are you? Can I trust you? Here are my

credentials

3. Verify identity and integrity (done locally)

3. Verify identity and integrity (done locally)

4. Session authorized 4. Session authorized

Cisco UCS 240 Server

Cisco CGR 1120

5. Open SSL session to rPi through CGR


Authentication Architecture for TNCRaspberry Pi

Cisco CGR 1120

Integrity Measurement Collector

Integrity Measurement Verifier

TNC IF-M (RFC 5792)

(Application layer)

TNC Client TNC ServerTNC IF-TNCCS (RFC 5793)

(Message Flow layer)

Network Access Requestor

Network Access Authority

TNC IF-T (RFC 6876)

(Packet flow layer)

Demo Network Topology

PT-TLS

Raspi 1

Raspi 6

Cisco CGR1120

…

UCS 7

UCS 9

HW TPMIMA

PT-TLS

TNC Client

TNC Server

IMA

TNC Client

SW TPM

TBOOT

TNC Client

HW TPMTBOOT

TNC ClientSW TPMTBOOT

TNC ClientPT-TLS

PT-TLS

http

http

IoT Devices

TNC Mutual Attestation

PolicyDB

TNC 1-Way Attestation

Fake endpoint


OK, Fine. Enough slides.

SHOW IT!


Sample Log Entries Showing System Start


Linux IMA to measure the OS• Prior to OS Load, the CRTM measures BIOS & boot loader into PCRs on the TPM• Early in OS Load, Linux Integrity Management Architecture measures (hashes) a

policy-based list of files and directories.• Each new hash is then extended into PCR 10• The final aggregate hash in PCR 10 is the record of the state of the measured

files/directories at time of boot• The quote of PCRs 0-7 and PCR 10 is the basis for TNC PDP to decide if the

supplicant OS is trusted

Snip of syslog showing IMA measuring file and extending measurements into PCR 10:(easiest to follow the numbers, read right to left)

PCR used (10) New value stored in PCR 10 Hash of file Hashed File

3. 2. 1. 4.


TNC Client Authentication – Certificate Exchange

Snippet of normal TLS certificate processing at session start, raspberry Pi requesting session with a CGR.Integrity validation follows certificate validation.


Authentication continues with validation of integrity report

Snippet from syslog showing completion of integrity validation done by a CGR against a raspberry Pi

TNC-based authentication of the rPi is now complete.A normal TLS session can now be set up.


Done with syslog, now the GUI view.

This screen shows the policy-defined list of directories and files that IMA will measaure into PCR 10 on the rPi.

When the rPi authenticates to the CGR, it provides a signed report of the values in its PCRs, including PCR 10.

This list is also kept in the validation server on the CGR, along with expected values for each file and each PCR.

The CGR only validates PCR measurements, not individual file measurements


Drill down on /bin directory, showing the files in /bin that are measured into PCR 10. The CGR will match the reported PCR 10 against the expected PCR to decide if the CGR trusts the OS running on rPi.


Final drill down – the SHA1 and SHA256 hash values that the CGR uses as golden values (customer selects which algorithm to use).

Remember that on the rPi, all these files are individually hashed (measured), then the hash extended into PCR 10 with all other hashes.

The CGR has a golden measurement for each file. It also has a golden measurement that represents the consolidated measurements of all the files consolidated in PCR 10.

At authentication, the CGR validates either each file measurement or only the consolidated set reported in PCR 10 by the rPi.

21

Next we look at the device report for devices currently connected to the CGR

This is a drill down on Raspi 2. Under Device Info, note the ID.

The ID is the SHA256 hash of Raspi 2’s AIK Public Key. The AIK private key is protected within Raspi 2’s TPM. This Proof of Concept uses the hash of the AIK public key as a unique, hardware protected identity for Raspi 2.

Hash of Raspi 2’s AIK public key

Device report, next


General report for Raspi 2

Click here to see details of the last session

23

TPM IMA on the rPi reporting 299 measurementsBased on policy in the CGR,

The CGR is validating every file. It expects 288 and finds them to be correctIt finds 299 measurements and ignores the 11 unknown“0 Failed” means that Raspi 2 is allowed to connect in this case

The “11 unknown” means there is a mismatch between what the Raspi 2 is reporting and what the CGR is expecting. If CGR is matching only on PCR 10, this would have been a “1 failed” condition and the session would not be allowed.

Connection attempt by Raspi 2 was allowed

Whoops! What happened here?

Here we are. One IMA generated hash was found to be different. Under the policy for this device, that is not acceptable.


What a server connection looks like on the CGR

Measurements of Linux follows TBOOT, assuming that the TPM quote is obtained through TXT running on the server

Server measurements are in PCRs 17 and 18 for Linux, therefore 2 evidence measurements are evaluated


Done & Summary

• This demo addresses a broad current of convergence occurring between the IoT & Cloud markets.

• We’ve seen – All devices in the demo employ multi-factor authentication to decide

whether a device can join the network or not.– That dedicated HW protects authentication credentials from end to end. – Two implementations of this authentication –

• One-way, the rPi to the CGR, the rPi implicitly trusts the CGR• Two-way, the CGR & the server – no implicit trust is required.

– A policy based mechanism for the customer to specify what software on the devices must maintain integrity and what happens when integrity is lost.

• The result is that devices in this network organize themselves into a closed communication path based on validation of HW protected identity and integrity information

Technology

Securing Internet of Things with Trustworthy Computing