A security system provides a defense from known and unknown viruses, worms, spyware, hackers, and unwanted software. The system can implement centralized policies that allow an administrator to approve, block, quarantine, and log file activities. The system can extract content of interest from a file container, repackage the content of interest as another valid file type, perform hashes on the content of interest, associate the hash of the container with the hash of the repackaged content, transfer the repackaged content, and store the hash with other security-related information.