1. A method for updating offline virtual machines, the method comprising: mounting an image of an offline virtual machine on a host operating system; generating drive-mapping information for the mounted virtual machine image; loading registry information of the mounted virtual machine image onto the host operating system using the drive-mapping information; determining an update to be applied to the offline virtual machine based on the registry information; retrieving a patch bundle based on the determination, wherein the patch bundle comprises: a patch file comprising the update to be applied to the offline virtual machine, registry update instructions configured to update the registry information based on the update to be applied to the offline virtual machine, and file system update instructions configured to update system files of the offline virtual machine as required to apply the update of the patch file to the offline virtual machine; and executing the patch bundle on the host operating system to update the registry information, update the system files of the offline virtual machine, and apply the update of the patch file to the offline virtual machine, wherein retrieving the patch bundle further comprises: recording virtual machine update information and file system modification information; writing the registry update instructions and the file system update instructions; retrieving the patch file; and bundling the patch registry update information, the registry update instructions and file system update instructions, and the patch file.