An updated virus pattern file is developed at an update server. A mobile management center (MMC) has a list of mobile telephone numbers and receives the new virus pattern from the update server. A Multimedia Message Service Center receives the new virus pattern and the list of mobile telephone numbers from the MMC and sends an MMS message to each of the wireless devices, including the new virus pattern as an attachment. Each wireless device replaces the old virus pattern with the new virus pattern. A unique identifier (a cryptographic signature or magic number) is added to each MMS message to enable the wireless device to recognize a new virus pattern. The pattern version and the pattern itself are merged into a single file. The file is also encrypted at the MMC and decrypted at the wireless device.