An Overview of Security Issues in the Web

1
An Overview ofSecurity Issues in the Web

• José KAHAN OBLATT
• W3C/INRIA
• jose_at_w3.org
• 19 December 1998

2
Disclaimer

• The following slides represent the authors
  personal opinion and not necessarily that of the
  W3C or of INRIA.

3
Outline

• Architecture Web
• Security problems
• Security measures
• Conclusion

4
Architecture of the Web

• Hypertext information model (linking of
  documents)
• Client/Server consultation protocol

?
Internet
documents
5
Security problems confidentiality

• Unauthorized release of information

?
Internet
user
?
pirate
6
Security problems integrity

• Unauthorized modification of information

user
?
pirate
7
Security measures
firewalls
encryption
Access control
authorization
authentication
8
Encryption principles

• Mathematical transformation of a message

Encrypt
Decrypt
Hello
Hel
Hello
plaintext
cyphertext
plaintext
decryption key
encryption key
-Document confidentiality -Document integrity
-Server authentication -Client authentication
9
Encryption mechanisms

• Symmetric (secret key) cryptographySame key used
  for encryption and decryption
• Asymmetric (public key) cryptographyDifferent
  keys used for encryption and decryption
• Supported by commercial browsers SSL, TLS
• BUT legal problems in some countries

10
Access control model
guard
authorize
Reference Monitor
noeuds
operation
deny
consult
update
security database
security administrator
11
Access control authentication

• Verifying the identity of a user

identity, proof of identity
security database
12
Web authentication mechanisms
13
Access control authorization

• Verifying the access rights of a user

identity, proof of identity
?
security database
14
Web authorization mechanisms

• Access control lists (ACL)

• Roles, groups simple user administration
• Capabilities exchange of access control
  information in the request

15
Personal experience

• Existing security mechanisms can solve most of
  the problems of confidentiality and integrity
• Difficult part defining a security policyset of
  rules describing the behavior of users in a
  system
• Choice of security mechanismsperformance versus
  simple user administration
• User education is important

16
Some security issues in EMGnet

• Encryption of data exchanges?
• Which authentication mechanism?
• Distribution or centralization of security
  database?
• Set of access rights?
• ACLs, capabilities, or both?
• User administration!
• Tip reuse existing technology when possible