Access Mode Validation for Home NodeB Security
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Solution Overview
Problem
Home NodeB (H(e)NB) cells deployed in insecure environments can be maliciously modified to conduct 'Man-in-the-Middle' attacks by altering their advertised Access Mode, allowing unauthorized access and eavesdropping of secure user communications.
Innovation Solution
The comparison of Access Mode and Closed Subscriber Group (CSG) Identifiers seen by User Equipment (UE) over the air with those reported to the Core Network (CN) is implemented to prevent such attacks, with corrective actions taken if a mismatch is detected, such as disallowing UE attach or denying service to the H(e)NB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If H(e)NB cells are deployed in insecure environments for improved in-house radio coverage, then service availability and accessibility are improved, but security and integrity of communications deteriorate due to possibility of malicious modification
Solution Approach 1:
The system performs preliminary verification of Access Mode and CSG ID consistency between over-the-air advertisements and core network reports before allowing UE attachment. This preventive check stops malicious cells from establishing secure connections in the first place
Solution Approach 2:
The system establishes a feedback loop where UEs report the Access Mode and CSG ID they observe in over-the-air advertisements back to the core network. This feedback mechanism enables continuous monitoring and detection of malicious modifications
2Ease of operation
If H(e)NB advertises restricted Access Mode to attract specific UEs, then selective access control is improved, but vulnerability to Man-in-the-Middle attacks increases due to configuration mismatch opportunities
Solution Approach 1:
The core network performs preliminary consistency verification of Access Mode and CSG ID before authorizing UE attachment. This pre-check prevents attackers from exploiting configuration mismatches to establish malicious connections
Solution Approach 2:
The core network acts as an intermediary that mediates between the H(e)NB advertisement and UE access requests. It verifies the consistency of Access Mode and CSG ID information, preventing direct exploitation of mismatches by attackers
3Object-generated harmful factors
If H(e)NB reports different Access Mode to Core Network than advertised over air, then attacker can grant unauthorized access, but detection capability is improved through consistency verification
Solution Approach 1:
UEs provide feedback to the core network about the Access Mode and CSG ID they observe in over-the-air advertisements. This feedback enables the core network to detect inconsistencies between advertised and reported configurations
Solution Approach 2:
The system performs preliminary detection of configuration mismatches during the initial attachment phase. By checking consistency before full service establishment, the system can identify and block malicious H(e)NBs early
Data Source
AI summary
An example method includes receiving at a User Equipment (UE) a value for an Access Mode identifier and a value for a Closed Subscriber Group (CSG) identifier in one or more cell advertisements, selecting a cell based on the or more cell advertisements, and reporting in a message the value of the Access Mode identifier and the value CSG identifier for the cell advertisement of the cell selected. A core network element receives a first Access Mode identifier value and a first CSG identifier value, these first values associated with a cell advertisement of a cell selected by a UE; receives a second Access Mode identifier value and a second CSG identifier value, these second values reported by the cell selected by the UE; performs a comparison of first and second Access Mode identifier value and/or first and second CSG identifier values; and takes action based on the comparison.