WEB SECURITY SSL

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WEB SECURITYSSL

• Presented by
• Samia Gad Omar
• March 2005

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Contents

• Handshake Protocol
• SSL Record Protocol
• Change C-Spec Protocol
• HTTPS
• SSL 3.0 Analysis
• Conclusion
• References

• Introduction
• Network Security Services
• Web Security Threats
• Web Security
• What is SSL?
• SSL Services
• SSL Architecture

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Introduction

• Virtually all businesses, most governments
  agencies, and many individuals now have Web
  sites, the number of sites expanding rapidly. As
  a result, businesses are setting up facilities on
  the web for electronic commerce. This explosive
  growth of the Internet and the World Wide Web has
  brought with it a need to securely protect
  sensitive communications sent over this open
  network.

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Network Security Services

• Authentication the assurance that the
  communicating entity is the one that is claims to
  be.
• Data Confidentiality the protection of data from
  unauthorized disclosure.
• Data Integrity the assurance that data received
  are exactly as sent by an authorized entity.
• Non Repudiation provides protection against
  denial by one of the entities involved in the
  communication.
• Access Control the prevention of unauthorized
  use of a resource.

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Web Security

• Web Security can be divided into three main
  parts
• Naming objects and resources securely.
• (Secure DNS, Self-certifying names,)
• Secure authenticated connection.
• (SSL Secure Sockets Layer)
• Mobile Code Security.
• (Most of the pages now a days contain
  executable code, including Java applets, ActiveX
  controls, and Java scripts.)

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Web Security Threats
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What is SSL?

• In 1995 Netscape Communication Corp, introduced a
  security package called SSL (Secure Socket Layer)
  to meet the demands for secure connections.
• SSL is a protocol that transmits your
  communications over the internet in an encrypted
  form. SSL ensure that the information is sent
  unchanged, only to the server you communicate
  with.
• Online shopping sites frequently use SSL
  technology to safeguard your information and
  financial transactions.
• In 1996 Netscape Communication Corp, turned SSL
  over to IETF for standardization, the result was
  TLS (Transport Layer Security).

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SSL Services

• SSL builds a secure connection between two
  sockets, including
• Parameter negotiation between client and server.
• Mutual authentication of client and server
• Secret communication
• Data integrity protection.

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SSL Architecture

• SSL is a new layer interposed between the
  application layer and the transport layer.
• SSL is divided into two layers
• 1- Upper layer a key exchange protocol which
  initializes and synchronizes cryptographic state
  at the two endpoints.
• 2- Lower layer compression and encryption of
  sensitive application data.
• SSL supports a variety of different algorithms
  and options.

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Handshake Protocol

• It is the most complex part of SSL. It consists
  of a series of message exchanged by client and
  server.
• Phase 1 Establish security capabilities,
  including protocol version, session ID, cipher
  suite, compression method, and initial random
  number.
• Phase 2 Server may send certificate key
  exchange, and request certificate.
• Phase 3 Client sends certificate, key exchange,
  certificate verification.
• Phase 4 Change cipher suite and finish handshake
  protocol.

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SSL Record Protocol

• The protocol takes an application message to be
  transmitted, fragments the data into manageable
  blocks, optionally compresses the data, applies
  MAC, encrypts, adds a header, and transmits the
  resulting unit in a TCP segment. Received data
  are decrypted, verified, decompressed, and
  reassembled and then delivered to higher level
  user.

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HTTPS
Change Cipher Spec Protocol

• This protocol consists of a single message, the
  purpose of it is to cause the pending state to be
  copied in to the current state, which updates the
  cipher suite to be used on this connection.

• HTTP is called Secure HTTP (or HTTPS) when it is
  used over SSL.

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Alert Protocol

• This protocol convey SSL-related alerts to the
  peer entity.
• Alert message are compresses and encrypted.
• First byte convey the severity of the message,
  warning or Fatal.
• Second byte contains the code of the alert
  (failure, illegal parameter, unknown
  certificate,).

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The network is weaker than the weakest point in
the network
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SSL Analysis

• SSL 3.0 aims to provide Internet client/server
  applications with a practical, widely applicable
  connection-oriented communications security
  mechanism. A number of minor flaws in the
  protocol and several new attacks on SSL are
  presented.

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The Key Exchange Layer Analysis

• The most important attacks are of the type man-in
  the middle attacks
• Dropping the change cipher spec message.
• Key-exchange algorithm rollback.
• Version rollback attacks.

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The Key Exchange Layer Analysis

• Dropping the change cipher spec message

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The Key Exchange Layer Analysis

• Key-exchange algorithm rollback.

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The Key Exchange Layer Analysis

• Version rollback attacks

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The Record Layer Analysis

• Confidentiality Eavesdropping.
• Confidentiality Traffic analysis
• Confidentiality Active attacks
• Cut-and-Paste attack, Short-block attack.
• Message Authentication HMAC.
• Replay Attacks
• The Horton principle
• Authenticate what was meant, not what was said

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Conclusion

• The protection of application data by the SSL
  record layer is quite good.
• The SSL handshake protocol has several
  vulnerabilities and worrisome features. Most of
  the weaknesses (active attacks) described
  previously arise from a small oversight and can
  be corrected without overhauling the basic
  structure of the protocol, of course , they are
  still worth fixing.
• In general SSL 3.0 provides excellent security
  against passive attacks.

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References

• A. S. Tanenbaum, Computer Networks, 4thedition,
  2002, Prentice Hall, Ch 8.
• W. Stallings, Cryptography and Network Security
  Principles and Practice, 3rdedition, 2003,
  Pearson Education, CH 17.
• Analysis of the SSL 3.0 potocol, David Wagner
  Bruce Schneier.

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Thank You