Areses is a rapidly spreading Internet worm that propagates by e-mail through messages with infected attachments. Once the user opens such an attachment, the parasite secretly installs itself to the system and runs a spreading routine. It gathers e-mail addresses from various local files and sends itself there using own integrated mail server. The worm’s payload is quite dangerous. Areses opens a back door providing the attacker with unauthorized remote access to the compromised computer. The worm can also open predetermined web sites without asking for user permission, close opened Internet Explorer windows and inject malicious code into legitimate system processes. Areses runs on every Windows startup.