Systems and methods for network access security

A system, comprising:

• at least one device configured to:
• receive an attach request associated with a user device attempting to attach to a network, wherein the attach request includes an international mobile equipment identity (IMEI) and an international mobile subscriber identity (IMSI);
• determine whether the IMEI is associated with a user device that is not allowed to attach to the network;
• determine, in response to determining that the IMEI is not associated with a user device that is not allowed to attach to the network, whether the IMSI included in the attach request is stored in a database;
• determine, in response to determining that the IMSI is stored in the database, whether an IMEI associated with the IMSI is stored in the database;
• determine, in response to determining that the IMEI associated with the IMSI is stored in the database, whether the IMEI stored in the database matches the IMEI included in the attach request;
• and
• deny the attach request in response to determining that the IMEI stored in the database does not match the IMEI included in the attach request.

A non-transitory computer-readable medium having stored thereon sequences of instructions which, when executed by at least one processor, cause the at least one processor to:

• receive a mobile equipment identity check request (ECR) message, wherein the ECR message includes an international mobile equipment identity (IMEI) and an international mobile subscriber identity (IMSI);
• determine whether the IMEI is associated with a user device that is not allowed to attach to the network;
• determine, in response to determining that the IMEI is not associated with a user device that is not allowed to attach to the network, whether the IMSI included in the attach request is stored in a database;
• determine, in response to determining that the IMSI is stored in the database, whether an IMEI associated with the IMSI is stored in the database;
• determine, in response to determining that the IMEI associated with the IMSI is stored in the database, whether the IMEI stored in the database matches the IMEI included in the attach request;
• and
• deny the attach request in response to determining that the IMEI stored in the database does not match the IMEI included in the attach request.