A client computer may be configured to perform computer security operations in conjunction with a remotely located security server. Upon detection of a computer security event, such as reception of a file, the client computer may generate a query input and determine if the query input has corresponding security information in the security server. When the query input has corresponding security information, the client computer may forward the query input to the security server. In response, the security server may retrieve the security information using the query input and provide the security information to the client computer. As a particular example, the security event may be reception of a file in the client computer and the security information may indicate whether or not the file is infected with a computer virus.