SMS Fraud Detection via HLR Validation
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Solution Overview
Problem
The increasing problem of fraudulent SMS messages entering networks due to the exploitation of 'grey routes', where legal interconnect agreements are exploited for illegal SMS traffic, making it difficult to detect and prevent unauthorized message delivery.
Innovation Solution
A method that involves querying and validating the legitimacy of message delivery routes by comparing address ranges of SMS Service Centres and Home Location Registers (HLRs/HSSs) across foreign PLMNs, using operations like SRI-for-SM and ATI to authenticate the originator and validate the message route before delivery, thereby identifying and preventing grey routes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If indirect routes (interconnect hubs or operator interconnect routes) are used for SMS delivery to reduce costs, then SMS delivery cost is reduced, but the risk of fraudulent message delivery increases due to grey routes exploitation
Solution Approach 1:
The system performs preliminary validation of the originating switch (MSC) address against the expected address derived from HLR query responses before allowing message delivery. This advance verification prevents fraudulent messages from being delivered through grey routes while maintaining cost-effective indirect routing.
Solution Approach 2:
The system introduces an intermediary validation mechanism that acts as a mediator between the message routing process and the actual delivery. By validating the originating switch address through HLR queries and comparing it with expected addresses, the system creates a security layer that prevents fraud without blocking legitimate cost-effective routing.
2Measurement precision
If message routing validation is performed to detect grey routes, then detection precision of fraudulent activities is improved, but device complexity increases due to additional validation operations
Solution Approach 1:
The system uses the existing HLR query mechanism, which is already part of the standard SMS delivery process, to serve multiple functions: both routing information retrieval and fraud detection. By validating the originating switch address using the same HLR response data, the system achieves high detection precision without adding separate complex validation infrastructure.
3Reliability
If originating switch address validation is performed for all incoming MT SMS traffic, then reliability of message delivery is improved by preventing fraud, but loss of time increases due to additional query operations
Solution Approach 1:
The validation of the originating switch address is performed as a preliminary step using the HLR query response that is already obtained during the normal message routing process. Since the HLR query is already executed to obtain routing information, the additional validation operation leverages this existing data without requiring separate time-consuming queries.
Data Source
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AI summary
A receiving network (MNO 2) detects fraudulent messages received via a grey route including for example a foreign network (MNO 1). At the start of the session a message delivery request (1) is sent to an SMS node (201) in the receiving network. This sends (step 2) a request to the HLR (102) of the supposedly originating network (MNO 1) for routing information concerning the originator. Upon receiving the response from the HLR (102), it requests validation of the retrieved information as listed in (step 203), to validate both the originator and the originating network (MNO1). The SMS node (201) also makes the conventional HLR (202) look-up for the recipient (step 4), before performing message delivery (step 5).