Yimshell.A is a flooder type hacking tool.
A flooder sends multiple information packets in order to block the target computer.
A flooder is normally used to attack IRC channels or standalone computers. It can also result in a denial of service (DoS) if the attacked computer is a server.
Yimshell.A prevents access from programs to websites of several companies related with security tools (antivirus programs, firewalls, etc.).
Yimshell.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.
Yimshell.A redirects attempts to access several web pages to a specific IP address.
Yimshell.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.