Security in WAP

1
Security in WAP

• Sanket Naik, Ameya Varde
• CS590F Fall 2000

2
Motivation and Goals

• To study the security issues in WAP
• To analyze an existing implementation and
  implement enhancements
• To investigate security holes in the
  implementation and WAP in general
• To suggest improvements for both

3
Implementation

• WAP stack from Kannel (www.kannel.org)
• An on-going open source project implementing the
  WAP stack
• No WTLS support
• WTLS layer from 3ui.com (www.3ui.com)
• We identified 2 security enhancements
• SSL connection between WAP gateway and Content
  (HTML) server
• Authentication of the WAP gateway by the WAP
  client
• Both missing in WTLS patch from 3ui

4
Kannel architecture
5
Security Enhancements
6
Development tools

• Platform Linux
• OpenSSL crypto library (http//www.openssl.org)
• NOKIA WAP Toolkit (http//www.forum.nokia.com)
• Simulates a web-enabled NOKIA 7110 phone

7
WTLS optimizations

• Why optimize?
• Low bandwidth
• Less processing power
• Less memory
• Weaker power supply
• The optimizations
• Abbreviated handshake using pre-master secret
  from previous session
• Optional steps Client can send NULL reply to
  Certificate request, Anonymous key exchange etc.

8
The flaws

• Encryption not truly end-to-end
• Abbreviated handshake susceptible to replay
  attack
• Chosen plain-text attack IV for each packet
  Sequence number XOR Original IV
• DOS attack Alerts are unauthenticated
• Man-in-the-middle attack 40 bit XOR MAC allows
  even bit changes
• Impersonation Anonymous key exchange methods
  allow key generation w/o Authentication (Kannel
  WTLS has only anonymous key exchange methods!)
• Weaker encryption mechanisms due to export
  regulations

9
Suggestions

• WAP specifications
• Enforce Client authentication rather than keep it
  optional
• Make WTLS layer mandatory whether people use it
  or not.
• Implementation
• Provide Gateway authentication in WAP clients
• Add stronger algorithms, keys and key exchange
  methods to the cipher suites

10
Conclusions

• WTLS Specs propose weak security
• Developers and Manufacturers are deploying WAP
  stacks which do not meet even these weak security
  requirements
• Mostly due to lack of security expertise
• Open source exposing these weaknesses
• Yet additional code review required
• Our 2 bits should be checked in soon