Transcript Unifying the conceptual levels of network security through use

Unifying the conceptual levels
of network security through
use of patterns
Ph.D Dissertation Proposal
Candidate: Ajoy Kumar, Advisor:
Dr Eduardo B. Fernandez
Introduction
• We analyze security mechanisms and the
protocols at the different network layers
and propose a unification of these levels
using security patterns. We also develop
several new patterns and study the
existing patterns for this purpose
General Goal
• In this dissertation our primary aim is to
unify the security functions used in
different network layers through security
patterns. We identify the common security
components of each layer and their
protocols and try to discover the existing
security patterns for each of these layers
and identify the missing patterns in order
to develop them.
Specific Goals
• Survey the existing protocols for each of these network layers in
detail such as IPSec, TLS and SAML.
• Survey the security mechanisms such as firewalls, IDS and VPN in
detail.
• Survey the existing patterns for each of these security components
for each of the network layers.
• Study the coexistence and synergy of one or more of these security
components.
• Identify and develop the patterns yet to be developed for the security
components for each of these network layers.
• Identify and develop the security patterns yet to be developed for
protocols at these layers.
• Identify the relation between these patterns.
• Apply the newly developed patterns to a case study and study the
effect of using security patterns.
Contributions
• A description of the three basic architectural
layers using pattern diagrams showing the
relationship between these patterns
• A description of the protocols to provide security
for these layers using security pattern maps.
• An enumeration of the use cases and the
security threats involved for the typical network
functions.
• Analysis of the existing countermeasures, e.g..
firewalls, IDS, VPNs and their combinations. We
will consider existing commercial products as
possible sources of security patterns.
Contributions (Contd…)
• Specific patterns for the network architectural
layers, their security standards, and
mechanisms to defend against the identified
threats. We have already published one of these
[Fer05] and in the process of completing
another.
• Helps a designer to understand a complex
system and helps him to design a secure
system.
• Validation of the approach to applying it to a
SCADA system.
Network Layer Security Patterns
• Italics – Already Existing Patterns
Firewall
IDS
VPN
Secure
Protocol
User
application
XML FW
XML IDS
XML VPN
SAML
TCP
Proxy FW
TCP IDS
TLS/SSL
VPN
TLS
IP
Packet
filter
Packet
IDS
IPSec VPN
IPSec
TLS/SSL
• Two protocols are dominant today for
providing security at the transport layer:
the Secure Sockets Layer (SSL) Protocol
and the Transport Layer Security (TLS)
Protocol. The latter is actually an IETF
version of the former
TLS Protocol
HTTP
LDAP
IMAP
…
Application Layer
Network Layer
TLS
TCP/IP Layer
TLS (Contd…)
• TLS is a connection-oriented protocol that provides
a secure channel between a client and a server.
TLS supports confidentiality, data integrity, and
client/server authentication. The TLS handshake
protocol provides a means for authentication and the
negotiation of security parameters, such as the
encryption algorithms, encryption keys, MAC keys,
etc., that are used to transmit data securely. The
TLS record protocol specifies how application data is
actually transmitted between two communicating
hosts so that confidentiality and data integrity are
provided.
TLS
• Has three responsibilities
– Server Authentication
– Client Authentication
– Encrypted Connection
TLS Handshake Protocol
• Client/server authentication in TLS is
handled in the handshake protocol.
• The TLS handshake has four phases.
• In the first phase, the client and server
exchange hello messages that are used
to establish security parameters used
in the TLS session and settings used
during the handshake, such as the key
exchange algorithm.
TLS Handshake
• During the second phase, the server
sends a Certificate message to the
client that may include a server
certificate when an RSA key exchange
is used, or Diffie-Hellman parameters
when a Diffie-Hellman key exchange is
used. The server may also request a
certificate from the client using the
CertificateRequest message.
TLS Handshake
• During the third phase of the handshake, the
client may send its certificate to the server in a
Certificate message along with a
CertificateVerify message so that the server
can verify certificate ownership, if the server
requested a client certificate during the second
phase. The client must send either a premaster secret encrypted using the server’s
public key, or public Diffie-Hellman
parameters, in the ClientKeyExchange
message so that the client and server can
compute a shared master secret
TLS Handshake
• In the fourth phase of the handshake,
the client and server finish the
handshake so that they may begin
exchanging application data.
Example
• Applications protocols such as HTTP,
LDAP, IMAP need to use TCP/IP to
support typical application tasks such as
displaying web pages or running email
servers.
Context
• TCP/IP governs the transport and routing
of data over the internet. We need a
protocol at the transport layer to allow the
server to be authenticated to the client and
vice-versa and establish a secure
connection between the two.
Forces
• Authenticate the server to the client
• Allow the client and server to select the
cryptographic algorithms, or ciphers, that
they both support.
• Authenticate the client to the server
(Optional)
• Use public-key encryption techniques to
generate shared secrets.
• Establish an encrypted TLS connection.
Solution
• The server has been authenticated to the
client and the client if needed is
authenticated to the server and an
encrypted connection is established
between the server and the client.
Class Diagram
Server
Client
TLS
*
requestService
*
*
requestService
*
Handshake
Authentication
Encryption
Algorithm
Sequence Diagram of Handshake
Protocol
:Client
:TLS
Hello
sendCertificate
:Server
Hello
sendCertificate
certificateRequest
helloComplete
sendCertificate
clientKeyExchange
verifyCertificate
Handshake completed
Consequences
• Advantages
– Server is authenticated.
– Client also can be authenticated if needed.
– We can use a strong RSA Key method for
server authentication.
– Once a strong hand shake is done a secure
channel is established.
Disadvantages
• The server specifies a list of
distinguished names of certifying
authorities that the server trusts when
it requests a client certificate. In
contrast, the client has no such
opportunity.
• Man in the middle attack.
Known Uses
• Any application that uses the TCP layer
which uses TLS and uses the handshake
protocol such as HTTP, LDAP, IMAP etc.
Related Patterns
• Authentication Pattern
• Patterns for Encryption Algorithms