It infects PE files, creates a backdoor that opens TCP port 2556 and ends processes belonging to security applications. It stops functioning after December 31, 2005.

Windows XP/2000/NT/ME/98/95

Bagle.O is a virus that has worm characteristics. Bagle.O infects PE files, increasing their size by 44 KBytes.

Bagle.O spreads via e-mail in a message with variable characteristics, and an attached file with an icon similar to Windows Notepad. It can also spread through peer-to-peer (P2P) file sharing programs.

Bagle.O contains a backdoor, which opens the TCP port 2556.

In addition, Bagle.O ends the processes belonging to several antivirus programs, firewalls and system monitoring tools. It also ends the processes belonging to previous variants of the worms Bagle and Netsky.

This worm only runs if the system date is December 31, 2005 or previous. After this date, Bagle.O stops functioning.

Bagle.O is easy to recognize, as it reaches the computer in an e-mail message with an attached file that has an icon similar to Windows Notepad: