When a network client accesses a file in a network file server, the network file server invokes a conventional virus checker program in an NT file server to transfer pertinent file data from the network file server to random access memory in the NT file server to perform an anti-virus scan. Users may interact with the virus checker program in the usual fashion, to select file types to check, and actions to perform when a virus is detected. This method eliminates the need for porting the virus checker program to the network file server, and avoids maintenance problems when the virus checker program is updated or upgraded. Moreover, a kernel mode driver in the NT file server may provide an indirect interface to the virus checker program for initiating an anti-virus scan. Therefore, the driver supports a wide variety of virus checker programs and ensures continued operation when the virus checker program is upgraded.