Worm Darby spreads via file-sharing networks, by e-mail and through IRC channels. Once executed, it shows a fake error message and installs itself to the system. It places infected executables in shared directories of peer-to-peer clients and tricks other users into downloading and installing these files. For spreading by e-mail the worm uses Microsoft Outlook mail program . It sends infected messages to addresses in the Address Book. Darby also may infect some personal documents and download its plugins from the Internet .