Disclosed are techniques for performing an antivirus task in a mobile wireless device running an embedded operating system. In one embodiment, calls intended for an application programming interface (API) function code is redirected to an antivirus function code. The redirection to the antivirus function code may be performed by modifying a kernel structure to point to a modified entry list instead of an API entry list. The redirection to the antivirus function code may also be performed by modifying the API function code to allow the antivirus function code to execute before the API function code. The kernel structure or the API function code may be properly restored back to its original form. Software implementations of these techniques may be readily loaded and unloaded, and may not require re-installation of the embedded operating system.