CRIS 2004 Communication Security Intro

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(No Transcript)
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Communication Infrastructure Security
Definitions and Concepts
Caroline DEURVEILHER Ludovic PIETRE-CAMBACEDES
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Scope

• This primer is about security, not about
• reliability, relating to accidental failures
• safety, dealing with the impact of these failures
  on the system environment
• But, what do we mean by security ?
• Prevention of unauthorized actions by users of a
  communication/computer system
• This afternoon, we want to
• Target an audience of non-specialists in the
  field
• Introduce the basic concepts and terminology of
  communication security
• Objectives
• Increase awareness of the different risks related
  to communication infrastructures
• Share common notions and vocabulary
• Get familiar with all the common words of
  communication security Firewalls, VPN, PKI,
  encryption
• Exchange experiences and visions

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Agenda

• Part I Basic notions
• Setting the scene
• Threats, attacks, vulnerabilities, risks
• The basic services of communication security
• Part II Security Mechanisms and Solutions
  Overview
• Elements of cryptography
• Certificates Public Key Infrastructure (PKI)
• Virtual Private Networks (VPN)
• Secure communication protocols
• Firewalls and secure architectures
• Part III End-to-End Security Approach
• Beyond technology, an end-to-end security
  approach
• Challenges in securing critical infrastructures
• Part IV QA
• Questions answers, debate

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Part IIntroduction
Part IIntroduction
Part IIntroduction
Part IBasic Notions
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Setting the scene
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Communicate anywhere, anytime, all sorts of
  information
• A symbol Internet. Interconnection of millions
  of networks
• Communication Infrastructure for Utilities

•  corporate  intranet
• Every day tools web, mails
• Business applications, CRM

•  industrial  network
• Control systems
• Monitoring systems

Internet
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What are the threats ?
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Types of threats to communication infrastructures
• Information leakage
• Data corruption (alter/damage/destroy)
• Spoofing
• Denial of Service (DoS)
• Concretely
• Trade secrets theft
• Silent modification of sensitive data
• Identity usurpation
• DoS on critical infrastructures
• Threat agents
• Insiders,
• Independent hackers, Virus writers,
• Criminal groups, Competitors,
• Foreign governments agencies

Likely origins, from the 8th CSI/FBI Computer
Crime and Security Survey (2003)
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Attacks, Vulnerabilities and Risks
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Some basic attack methods
• Eavesdropping
• Man-in-the-middle attack
• Bypassing
• Replay
• Flooding
• Vulnerabilities
• No security measures
• Weaknesses in safeguards
• Risks
• Complex notion
• Bound to probability of success of a
• given type of attack and the gravity of the
  consequences

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Some interesting figures
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers
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Getting more formal ISO approach
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers
From ISO-15408
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The fundamental services of information security
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Confidentiality
• Prevention of unauthorized disclosure of
  information
• Maybe the best known aspect
• Integrity
• Prevention of unauthorized modification of
  information
• Everything is as supposed to be
• Availability
• Property of being accessible and useable on
  demand by authorized entities
• But as lists are never complete
• What about Authenticity ?
• Accountability / Non-repudiation (some assume
  them included in Integrity)
• Access Control (spread between Confidentiality
  and Availability)
• Authorization

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Part IIntroduction
Part IISecurity mechanisms solutions
Part IIntroduction
Part IIntroduction
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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• A fundamental tool in communication security
• kryptós (hidden), gráphein (to write), the
  science of secret
• Basic toolbox to implement the basic security
  services
• Quite a long and colorful history

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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Symmetrical Cryptography
• The same key is used to encipher and decipher
• The algorithm is known, the key is secret
  (Kerckhoffs) key distribution problem
• Secure standards exist and must be used (AES,
  T-DES)

Shared Secret Key
ùµ
Clear text
Clear text
Bob
Alice
( Careful, quite subjective notions !)
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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• The Advanced Encryption Standard
• NIST call in 97, 5 finalists in 99, Rijndael in
  00, FIPS in 03
• 128 bits blocks, 128 / 192 / 256 bits keys
• Best known attack exhaustive key search

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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Asymmetric cryptography
• Principle each user has a public key and
  private key
• Everybody knows about the public key
• All keep their private key for themselves
• No shared secret
• When something has been enciphered by one of the
  two keys, then it can only get deciphered by the
  other key
• The RSA algorithm is the most commonly used
• Based on the factorization problem
• Some very interesting properties
• Solves the puzzle of key distribution
• Fits to n-to-n electronic transactions
• Good tool to ensure the basic security mechanisms
  
• Confidentiality Authentication Integrity
  Non Repudiation Signature

Alices public key
Alices private key
Alice
Bob
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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Ensuring confidentiality
• The keys represented on the slide belong to Bob
• Alice enciphers its message with Bobs public key
• She got it easily, because it is a public data
• Only Bobs private key can decipher the message

Bobs private key
Bobs public key
ùµ
Clear text
Clear text
( Careful, quite subjective notions !)
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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Ensuring authentication
• The keys represented on the slide belong to Alice
• Alice enciphers her message with her private key
• Bob deciphers it with Alices public key.
  Everyone can do that.

Alices public key
Alices private key
ùµ
Clear text
Clear text
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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Hash or digest functions
• One way function, easy to compute
• Variable input size, fixed output size
• A small change in implies a big and
  non-predictable change out

Amount of data (can be large)
hash
hash
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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Electronic signature principles
• Alice signs a hash of the original document with
  her private key
• Bob deciphers this hash and compares it along the
  original one
• Senders authentication AND message integrity are
  guaranteed

Authentication v Integrity v Confidentiality X
Signature
ùµµù
ùµµù
hash
Alices private key
Alices public key
hash
Text to sign
hash
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Elements of cryptography
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Hybrid cryptography
• Combined use of symmetrical and asymmetrical
  cryptography
• RSA about thousand times slower than AES...

Authentication v Integrity v Confidentiality v
Bobs private key
Bobs public key

Clear Text
Clear text
Symmetric key agreement (gt confidentiality)
ùµ
Signature
Signature
Electronic signature appended (gt authentication
integrity)
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Public Key Infrastructures (PKI)
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Raw asymmetric cryptography has problems
• Masquerade Man-in-the-middle attack
• Necessity for a strong link between public key
  and the owner
• Certificates and Trusted Third Party come into
  play
• A TTP associates the key with the owner
  electronically
• The result is called a certificate
• A complete set of standards rules it
• ISO IETF X509v3 certificates

Alices key
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PKI, definition and architecture
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Certificates and key pairs a whole life cycle to
  manage
• Generation and distribution of key pairs /
  certificates
• Trust in the TTP, loss/theft of keys revocation
  renewal

• Generic architecture
• Certification Authority
• Single, hierarchy,
• Registration Authority
• On-line, face to face
• Publication Service
• Certificates and CRL
• End-entity
• Persons, machines

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Virtual Private Network (VPN)
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• VPNs allow private information to be transferred
  securely across a public network
• A private communication path through a shared
  public network
• A private communication path providing
  confidentiality, integrity and authenticity over
  a shared, untrusted network
• An extension of the network perimeter
• Site-to-Site Connectivity before VPN leased
  line

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VPN Topologies
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Site-to-Site Connectivity with VPN
• Reduced network infrastructure costs and
  increased information flow
• Technical goal provide secured site-to-site
  access over any public network
• Host-To-Site Connectivity with VPN secure remote
  access
• Business goal lower telecom costs, increase
  employee productivity
• Technical goal provide secured same-as-LAN
  access to remote workers
• Needs
• VPN Gateway for site access
• VPN Client for remote access

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VPN Technologies
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Based on the principle of  tunneling 
• Tunneling encapsulation of one protocol to
  another
• Tunneling protocols
• Tunneling protocols do not necessarily provide
  security (C.I.A.)
• Based on encryption protocols to secure tunnels
• IPSec
• SSL

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IP Security Protocol (IPSec)
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Definition
• Set of protocols developed by the IETF to support
  secure exchange of packets at the IP layer
• IPsec has been deployed widely to implement
  Virtual Private Networks (VPNs)
• IPSec can provide
• Data confidentiality
• Data authenticity (authentication and integrity)
• Authentication
• Access Control
• Two operational modes
• Transport mode
• Does not encrypt the entire packet
• Uses original IP Header
• Tunnel mode
• Encrypts entire packet including IP Header (ESP)
• Creates a new IP Header

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Secure communication protocols TLS/SSL
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• TLS Transport Layer Security, formerly known as
  SSL Secure Sockets Layer
• A protocol layer running on the top of layer 4
  TCP that provides
• End-to-End Confidentiality
• Message is encrypted so it cannot be read during
  transit
• Uses conventional cryptography with shared key
• Integrity protection
• Message Authentication Codes (MAC)
• Authentication
• Checks identities of participants
• Server authentication or/and client
  authentication (optional)
• Use of X.509 certificates
• SSL a standard way to secure Web communications
  

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Secure communication protocol SSH
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• SSH stands for Secure Shell Protocol
• A protocol layer running on top of layer 4 TCP
  that provides
• Data Confidentiality
• Data exchanged are encrypted between hosts
• Data integrity
• Use of HMAC (Hash Message Authentication Codes)
• Authentication
• Server and client authentication
• Methods password-based, public key-based
• Data compression
• Optional
• Intended to replace rsh, rlogin, telnetftp
• Secure Remote Command and consol execution
  (replace rexec)

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Firewall and secure architecture
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Basic Definition
• In building construction a firewall is designed
  to keep a fire from spreading from one part of
  the building to another
• In network security a component or a set of
  components that restricts access between a
  protected network and an untrusted network (like
  Internet)
• Functions
• The security system acts as a network gatekeeper
  by controlling network traffic that crosses the
  information security perimeter (inbound an
  outbound traffic)
• Creates a separation between public untrusted
  networks (like Internet) and private trusted
  networks by examining network traffic

Controlling network traffic let pass or block ?

Untrusted public Network
Trusted and protected Internal Network
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How does a firewall work ?
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• The real power of a firewall is derived from its
  ability to be selective about what it lets
  through and what it blocks its filtering
  capabilities
• The firewall effectiveness increases with the
  amount of information it gets about the data that
  go through it
• Types of firewall filtering
• Packet filtering
• Circuit filtering
• Application-Level Gateway

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What can do a firewall ?
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Focus on security decisions
• All the inbound and outbound traffic passes
  through the firewall
• Firewall is like a choke point
• Enforce a security decision
• Enforcing the site security policy
• Allowing only  approved  services
• Log Internet activity efficiently
• A good place to collect information about system
  and network use misuse
• Limits exposure create separated zones
• Use of internal firewalls
• Keep one section of your site network separated
  from another one

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What cannot do a firewall ?
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Doesnt protect against malicious insiders
• Attackers inside the private network
• Doesnt protect against connections that dont go
  through it
• Back doors inside the network via a dial-up modem
  connection
• Doesnt protect against viruses
• A firewall can only prevent a virus or Trojan
  that would be on your machine from accessing the
  internet
• 95 of all viruses and Trojans are received via
  e-mail, through file sharing or through direct
  download of malicious programs. For theses cases,
  only a good anti-virus software program provides
  the adequate solution.
• Doesnt set up itself magically
• Protection is a set of rules
• Configuration is essential

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Perimeter Network / De-Militarized Zone (DMZ)
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Basic definition
• A network added between a protected network and
  an external network, in order to provide an
  additional layer of security
• Function
• It is kept apart from the rest of the network so
  that an attacker cannot exploit the necessary
  weaknesses of the DMZ machines to compromise
  other machines in the private network
• Servers kept in a DMZ should be secured as
  strongly as possible
• Connections to them from the internal network
  should be undertaken as if they were going to any
  other host on the Internet

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Proxy
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Basic definition
• Something or someone who does something on
  somebodys behalf
• A program that deals with external servers on
  behalf of internal clients
• Functions
• Primarily functions  caching proxies 
• Keep copies of information for each request that
  they relay
• Improve network efficiency by reducing the load
  on network connections
• Security functions
• Provide replacement connections proxies handle
  all the communication between users and Internet
  services behind the scenes
• Can do intelligent filtering
• Can perform user-level authentication
• Proxy services are effective only when used in
  conjunction with a mechanism that restricts
  direct communications between the internal and
  externals hosts (firewall with packet filtering)

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Typical Firewall Architecture
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers
FW
FW
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Part IIntroduction
Part IIntroduction
Part IIntroduction
Part IIIEnd-to-End Security Approach
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End-to-End Security Approach
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Security is not just technical measures
• Technologies are nothing without people and
  process
• Physical security is to be considered
• End-to-end security approach
• Developing a security strategy and defining
  security policies
• Implementing security measures
• Training and consciousness of staff members and
  users
• Control and monitoring
• Risk Management

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Challenges in securing Critical Infrastructures
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Computerized control systems perform vital
  functions across many of our national critical
  infrastructures
• Electric power generation, transmission and
  distribution
• Oil and gas refining pipelines
• Water treatment and distribution
• Chemical production and processing
• Successful attacks on control systems could have
  devastating consequences
• Endangering public health and safety
• Damaging the environment
• Causing a loss of production, generation or
  distribution of public utilities.

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Challenges in securing Critical Infrastructures
Introduction I Security Mechanisms Solutions
Overview I End-to-End Security Approach I
Questions Answers

• Historically security concerns were in physical
  security
• Securing these critical infrastructures poses
  significant challenges
• Adoption of standardized technologies
• Before proprietary hardware, software and
  network protocols it was difficult to understand
  how control system operated
• Today usage of standardized technologies like
  the common protocols used by Internet (XML,
  HTTP)
• Connectivity to other networks
• Access to real-time information
• Monitor and control process control system from
  different points on the enterprise network
• Insecure Connections
• Vulnerabilities exacerbated by insecure access
  links-such as dial-up modems open for remote
  diagnostics, maintenance and examination of
  system status
• Control system communication protocols are
  insecure
• Management and control systems are inherently
  insecure
• Use of existing security technologies and
  practices is constrained
• Limiting processing capabilities

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Part IIntroduction
Part IIntroduction
Part IIntroduction
Part IVQuestions Answers
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Our favorite references

• Security news and awareness
• RISKS Digests (ACM, P.G. Neumann)
  http//catless.ncl.ac.uk/Risks/
• Cryptograms Bruce Schneiers newsletter
  http//www.schneier.com/crypto-gram.html
• General security portals www.sans.org
  www.infosysec.org
• The Twenty Most Critical Internet Security
  Vulnerabilities www.sans.org/top20/
• CERTs www.cert.org www.first.org national
  CERTs (in FR CERT-A, -IST, -RENATER, private
  CERTs)
• www.securityfocus.com, http//www.insecure.org/,
  www.antionline.com
• Norms and standards
• ISO/IEC 7498-2, "Open Systems Interconnection --
  Basic Reference Model -- Part 2 Security
  Architecture"
• ISO/IEC 15408, Information technology - Security
  techniques - Evaluation criteria for IT security
  
• ISO/IEC 17779, which gives a comprehensive set of
  controls comprising best practices in information
  security
• RFCs from the Internet Engineering Task Force,
  http//www.ietf.org/
• And so much more (IEEE, ANSI X9, PKCS)
• Cryptography
• Some books
• For technical references Handbook of Applied
  Cryptography by Alfred J. Menezes, et al
  (http//www.cacr.math.uwaterloo.ca/hac/)
  "Applied Cryptography" by Bruce Schneier
  "Cryptography Theory and Practice", by Douglas
  Stinson
• History vulgarization "The Code Book" by
  Simon Singh "The Codebreakers" by David Kahn

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Our favorite references

• Security solutions
• For secure protocols RFCs from the Internet
  Engineering Task Force, http//www.ietf.org/
• On firewalls
• Building Internet Firewalls by Elizabeth D.
  Zwicky, Simon Cooper and D. Brent Chapman
• On VPN
• Virtual Private Network Consortium,
  http//www.vpnc.org/
• Les VPN, Principes, conception et déploiement
  des réseaux privés virtuels, by Rafael Corvalan,
  Ernesto Corvalan and Yoann Le Corvic
• On Network Security
• Network Security, Private Communication in a
  Public World, by Charlie Kaufman, Radia Perlman
  and Mike Speciner
• Critical Infrastructure Security Reports
• Cyber Security of the Electric Power Industry,
  by Institute For Security Technology Studies At
  Dartmouth College, December 2002
• Information Security Primer, by EPRI, final
  Report, September 2000
• Critical Infrastructure Protection, by US
  General Accounting Office, GAO-04-140T
• Others

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Part IIntroduction
Part IIntroduction
Part IIntroduction
Thank you for your attention
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