Esmumo.A is a Trojan, which although seemingly inoffensive, can actually carry out attacks and intrusions.
It reduces the security level of the computer:
it listens on open ports in order to control the computer remotely; it changes system permissions, decreasing the security level.
Esmumo.A prevents access from programs to websites of several companies related with security tools (antivirus programs, firewalls, etc.).
Esmumo.A does not spread automatically using its own means. It needs an attacking user's intervention in order to reach the affected computer. The means of transmission used include, among others, floppy disks, CD-ROMs, email messages with attached files, Internet downloads, FTP, IRC channels, peer-to-peer (P2P) file sharing networks, etc.