Mulim is a backdoor that provides the attacker with unauthorized remote access to the compromised computer. The intruder can download and execute arbitrary files, run applications, list active processes, gather system information, update or uninstall the backdoor. Mulim is able to spread. It can propagate through instant messages using popular messengers like Yahoo! Messenger, MSN Messenger, AIM and ICQ. Mulim’s malicious messages contain links to the parasite and attacker-specified texts. The backdoor runs as a service on every Windows startup.