1. A signature rule processing method, comprising: receiving, by a cloud server, signature rule usage status information of at least one security device connected to the cloud server, which is sent by the at least one security device, wherein the signature rule usage status information of the at least one security device is used to indicate a usage status of a signature rule of the at least one security device in a network; performing, by the cloud server, correlation analysis on the signature rule usage status information of the at least one security device and a latest signature rule set published by the cloud server, to obtain a most active threat signature rule identification list; generating, by the cloud server, according to the most active threat signature rule identification list, update information corresponding to the at least one security device; and sending, by the cloud server, the update information to the at least one security device, to drive the at least one security device to update a signature rule according to the update information; wherein the performing step comprises: obtaining, according to the signature rule usage status information, a first threat signature rule ID set with a use frequency greater than a preset frequency and a second threat signature rule ID set with a hit count greater than a preset count in the network traffic; obtaining a third threat signature rule ID set with a danger coefficient greater than a preset threshold according to the latest signature rule set; obtaining, by the cloud server, a fourth threat signature rule ID set by calculating a union set of the first threat signature rule ID set, the second threat signature rule ID set, and the third threat signature rule ID set; and generating the most active threat signature rule identification list according to the fourth threat signature rule ID set.