Hosts.A is a Trojan, which although seemingly inoffensive, can actually carry out attacks and intrusions: screenlogging, stealing personal data, etc.
Hosts.A prevents access from programs to websites of several companies related with security tools (antivirus programs, firewalls, etc.).
Hosts.A redirects attempts to access web pages of certain banks to spoofed pages, with the aim of logging information entered by the user in these pages.
Hosts.A redirects attempts to access several web pages to a specific IP address.
Hosts.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.