IEEE 802.21 MEDIA INDEPENDENT HANDOVER DCN: 21-08-0054-00-0sec-mih-level-security-considerations Title: MIH-level Security Considerations Date Submitted: February 10, 2008 Presented at IEEE 802.21 session #25 in Orlando Authors or Source(s):  Yoshihiro Ohba (Toshiba) Abstract: This document describes security goals, use cases and considerations on MIH-level security. 21-08-0054-00-0sec

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Purpose Identify security goals for each service and use case Determine the level of requirement for each goal Levels of requirement M (Mandatory requirement) O (Optional requirement) - (Not required) 21-08-0054-00-0sec

Security Goals Data origin authentication Mutual authentication Unilateral authentication Message authentication Replay protection Confidentiality 21-08-0054-00-0sec

Use Cases Pre-attachment use case MIH entity communicates with another MIH entity before network access authentication Used for MIHF Discovery and Information Service Post-attachment use case MIH entity communicates with another MIH entity after network access authentication Used for all services and service management 21-08-0054-00-0sec

Goals and Requirements (Pre-attachment Use Case) Security Goals Requirement (M/O/-) Note Data origin authentication Mutual authentication Unilateral authentication Message authentication Replay protection Confidentiality TBD 21-08-0054-00-0sec

Goals and Requirements (Post-attachment Use Case) Security Goals Requirement (M/O/-) Note Data origin authentication Mutual authentication Unilateral authentication Message authentication Replay protection Confidentiality TBD 21-08-0054-00-0sec

Considerations on Pre-attachment Use Case (1/2) Pre-attachment use case is vulnerable to man-in-the-middle (MiTM) attack Scenario: An attacker AP-X resides between MN and AP-Y and bridges MIH discovery and MIH messages back and forth (1) MN discovers AP-X (2) MN establishes an SA with IS server of operator Y, and perform IS query over the SA. The IS server responds to the MN with operator-id “Y” and other information associated with operator Y. MN AP-X (lying) AP-Y (legitimate) IS server Operator X’s network Operator Y’s network (3) MN performs network access authentication with AP-X. If both operators X and Y have a roaming relationship with MN’s home operator, MN will be authorized for access to operator X’s network even if it thinks that it is attaching to operator Y’s network. One day, the user of the MN will receive a bill from the home operator about the use of operator X, which may be more expensive than expected. 21-08-0054-00-0sec

Considerations on Pre-attachment Use Case (2/2) The MiTM attack is possible even with (mutual or unilateral) data origin authentication at MIH-level To detect the MiTM attack, Channel Binding [RFC3748] needs to be provided for MIHF ID of PoS during network access authentication in step (3) However, Channel Binding is optional in all known link-layer technologies that use EAP, and no standard Channel Binding solution exists On the other hand, only limited types and amount of information will be provided to unauthenticated MN for security and resource reasons Question: Does the benefit of securing pre-attachment use case pay to its deployment cost? 21-08-0054-00-0sec