BIND: A Fine-grained attestation Service for Secure Distributed Systems

BIND: A FINE-GRAINED ATTESTATION SERVICE FOR

SECURE DISTRIBUTED SYSTEMS

Presented by:Maryam Alipour-AghdamUniversity of Guelph

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OVERVIEW Motivation BIND Overview BIND Interface BIND Properties Application of BIND

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OVERVIEW Motivation BIND Overview BIND Interface BIND Properties Application of BIND

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MOTIVATION To securing distributed systems To address issues such as:

difficulty in verification of hash due to variability in software verification and configuration

to address the time of use and the time of

discrepancy the code may be correct at the attestation time and

compromised at the use time.

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OVERVIEW Motivation BIND Overview BIND Interface BIND Properties Application of BIND

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BIND OVERVIEW

Security issue Byzantine attack: A remote software platform may

be compromised and run malicious code.

The purpose of using code attestation identify what software is running on a remote

platform

detect a corrupted participant

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BIND OVERVIEW BIND Proposed Properties

perform fine-grained attestation BIND attests only the piece of code instead of entire

memory content

narrows the gap between time-of-attestation and

time-of-use measures a piece of code immediately before it executed

use a sand boxing mechanism to protect the execution of

attested code

ties the code attestation with the data that the

code produces

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BIND OVERVIEW Distributed system model:

Process

Data

Intermediary

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BIND OVERVIEW Distributed system model:

Process a producer or consumer of data represent program logic a piece of software code which needs to be attested *

Data information exchange between the processes Primitive data : external input to distributed systems Derived data :

output of some process generated by applying protocol logic over some input data

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BIND OVERVIEW Distributed system model:

Intermediary medium over which data is communicated from/to a

process

network that forward the data between hosts

operating system that dispatches the data to the process

hard drive or any part of RAM outside the process

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BIND OVERVIEW

PCP BP A

LocalConfiguration

LocalConfiguratio

n

LocalConfigurati

on

1.1.1.1 2.2.2.2 3.3.3.3

Ping 3.3.3.3 -t 10Dest= 3.3.3.3,TTL=10

Dest= 3.3.3.3,TTL=9

PongPongPong

Figure 1. Simple Ping: The conceptual model for distributed protocols

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BIND OVERVIEW

Figure 1. Simple Ping: The conceptual model for distributed protocols

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BIND OVERVIEW

Figure 1. Simple Ping: The conceptual model for distributed protocols

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BIND OVERVIEW

Figure 1. Simple Ping: The conceptual model for distributed protocols

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BIND OVERVIEW

Figure 1. Simple Ping: The conceptual model for distributed protocols

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BIND OVERVIEW

Figure 1. Simple Ping: The conceptual model for distributed protocols

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BIND OVERVIEW

Figure 1. Simple Ping: The conceptual model for distributed protocols

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BIND OVERVIEW Ping-Pong Protocol:

Process PA, PB, and PC which runs on host A, B, and C

Data User command (primitive data) Ping pong messages (derived data) Local IP address of each host (primitive data)

Intermediaries network and operating system

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BIND OVERVIEW Security problems in distributed systems Byzantine attacker model:

Malicious intermediary and the data misuse attack

Malicious process and the data falsification attack

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BIND OVERVIEW Security problems in distributed systems Byzantine attacker model:

Malicious intermediary and the data misuse attack Threats:

alter and inject protocol data data misuse attack which use authenticated protocol

data in a malicious way Solution:

employ cryptography constructions Example: message authentication code, digital

signature

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BIND OVERVIEW Security problems in distributed systems Byzantine attacker model:

Malicious process and the data falsification attack Threats:

Injecting bogus data into the distributed systems (data falsification attack)

Traditional cryptography can not be used As malicious process has the correct cryptography keys

to disguise itself as a legitimate participant Example: a malicious process can modify the TTL field in

a ping message.

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BIND OVERVIEW Attestation Design Consideration

Coarse-grained attestation Attestation over entire software platforms

Fine-grained attestation attestation over a critical piece of code

create distinction between process and intermediary

to enable the notion of granularity in attestation

to create boundary between what code is being attested to and what is

not

both process and intermediary exist in the form of software code in reality

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BIND OVERVIEW Attestation Design Consideration

Fine-grained attestation properties

simplifies hash verification

perform software upgrade more easily as expected hash for

each process can be updated independently

allow distributed system architect to focus on the security of

critical module by singling it out form a complicated system

does not address intermediary attacks

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BIND OVERVIEW Desired Properties of BIND Attestation Service

should be free of all software attacks

process is correct at load-time

needs to be efficient

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BIND OVERVIEW Process and Data Integrity

Defining Process and Data Integrity

process is a piece of code (process)

when the data is primitive and is genuine (data integrity)

the data is derived by running a genuine process over

genuine data inputs (data integrity)

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BIND OVERVIEW Techniques to ensure the integrity of primitive data

Semantic Check Example: A distributed scientific computing application checks if an

input matrix is well-formed.

Certificates use a central trusted authority to sign certificate for primitive data

Trusted Path use trusted path mechanisms for input data to make sure the data

came from an authenticated user

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BIND OVERVIEW Techniques to ensure the integrity of process and derived

data Authenticator

is produced by BIND

Generates a process for every piece of data

Is attached to data through its life-time

Example: when the data is sent over the network, or stored and

fetched from local untrusted storage

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OVERVIEW Motivation BIND Overview BIND Interface BIND Properties Application of BIND

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BIND INTERFACE

1. Initiate an attestation phase2. Memory addresses of the process input data3. Size of process code

4. receiving the ATTESTATION-INIT request5. Verifies authenticator on input data

6. Hashes the process code along with input data7. If above step successful, yields control to the processor with a success indicator

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BIND INTERFACE

1. In response to ATTESTATION-COMPLETE command2. BIND computes an authentication tag over3. an output data

4. a hash of the process code5. Authentication tag binds the output data with the code that has generated it.

6. BINDs undoes the protection it has set up for the protection. 7. BINDs returns the authenticator to the process.

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OVERVIEW Motivation BIND Overview BIND Interface BIND Properties Application of BIND

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BIND PROPERTIESFine-grained Attestation:

ATTESTATION-INIT indicate the beginning of process ATTESTATION-COMPLETE indicates the end of process

Binding Process and Data Integrity derived data builds on the integrity of its generating

process integrity of a processes and data are inseparable from

each other in DC

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BIND PROPERTIESTransitive Integrity Verification

BINDs achieves this property with O(1) overhead.

Efficient TPM’s hardware-based cryptography engine is

utilized to enable fast cryptography computations

needed for attestation.

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BIND PROPERTIES

Trusted Platform Module (TPM)

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BIND PROPERTIESTPM in Attestation Overview

The signature on the input data is validated through

public signing key of TPM that signed the input data

Secure Kernel (SK) sends the output data to be signed

by TPM.

SK utilizes the TPM’ s hashing and digital signature

functionalities.

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BIND PROPERTIES A Symmetric Key Alternative

Asymmetric key cryptography has high computational overhead

A secret MAC key should be established between two TPMs.

TPM’ s SHA-1 function instantiate a MAC between TPMs. The key should be sealed in TPM’s memory and should

be remained invisible to untrusted party Example: application code, peripheral devices

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BIND PROPERTIES A Symmetric Key Alternative

The key are unsealed to the SK upon time of use which used by SK

to verify the MAC on input data compute the MAC over output data and the hash of process

code secret key remain in SK’s memory for a controlled period of time after usage the secret key should be destroyed SK should be executed in a globally uninterrupted manner to

prevent untrusted OS Kernel form reading off the secret key information

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BIND PROPERTIES A Symmetric Key Alternative

Diffie-Hellman for key exchange in BIND

K−1 (A) is private signing key for TPMAThe signing pair (K-1 (A), KA) is created inside TPM SHA-1 functionality presents MAC function using the TPM

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OVERVIEW Motivation BIND Overview BIND Interface BIND Properties Application of BIND

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APPLICATION OF BIND Securing distributed computation applications with BIND

master / slave structure master splits the job to tasks and send them to slaves

(participants). master process asks BIND to sign a task description before

sending slaves ask local BIND to verify the integrity of task description computation results be will signed by BIND along with an

integrity proof of the participant process master check whether the result is trustworthy after the results

reported to the master.

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APPLICATION OF BINDo BIND properties in distributed computing application Deterministic Guarantee

BIND guarantees what code has been run in generating the result.

General BIND is applicable to all types of distributed computation

application. regardless of what function we want to compute

Efficient For BIND, the entire code is measured only once regardless of how

many times each instruction executed.

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APPLICATION OF BIND BGP Overview

Border Gateway Protocol (BGP) a path vector routing protocol establishing a path to each existing prefix Autonomous System (AS) is a collection of routers under

one administrative domain. In BGP, neighbouring Ases exchange prefix information

through BGP Update messages. A BGP update message consists of a prefix along with a

ASPATH.

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APPLICATION OF BIND Attacks Against BGP

Prefix theft: unauthorized prefix announcement ASPATH falsification in BGP update messages Both attacks attract traffic to a point in the network

that would otherwise not receive the traffic. blackhole attack: allows an attacker to control packets

that it would otherwise have no control over.

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APPLICATION OF BIND Securing BGP using BIND

two main mechanisms we need to secure BGP verify the correctness of the origin of the prefix prevent a malicious AS from altering the ASPATH prefix is categorized as primitive data prefix integrity: we adopt the known certificate

approach, where a prefix owner obtains a prefix certificate from a trusted authority.

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APPLICATION OF BIND Securing BGP using BIND

use attestation for ASPATH use BIND interface for attestation create a trusted attestation service in each router ASPATH is cryptographically protected by a message

authentication code

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CONCLUSION fine-grained attestation technique narrow the time of use and time of attestation establishes a trusted environment for

distributed systems simplify the design of distributed system a hardware design base of BIND is considered

for future work

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Thank you