Bagle (also known as Beagle) was a mass-mailing computer worm affecting Microsoft Windows.
[3][4][1] It copies itself to the Windows system directory (Bagle.A as bbeagle.exe, Bagle.B as au.exe), adds HKCU run keys to the registry, and opens a backdoor on a TCP port (6777 for Bagle.A and 8866 for Bagle.B).
[5] It was much more widespread and appeared in large numbers; Network Associates rated it a "medium" threat.
At one point in 2004, the Bagle and Netsky viruses exchanged insults and harsh words with each other in their codes, beginning with Bagle.I on March 3, 2004.
[6] Notably, Bagle.J contained the message “Hey, NetSky, fuck off you bitch, don't ruine our bussiness, wanna start a war?”, and Netsky-R included, "Yes, true, you have understand it.
Additionally, on July 3 and 4, 2004, Bagle.AD and Bagle.AE were released, with the source code for the virus, written in Assembly, visibly appearing in both of them.
It was estimated that the botnet was responsible for about 10.39% of the worldwide spam volume on December 29, 2009, with a surge up to 14% on New Year's Day,[18] though the actual percentage seems to rise and drop rapidly.