Cutwail botnet hit (briefly) by Latvian ISP closure
According to the August edition of the MessageLabs Intelligence monthly report, Real Host (an ISP based in Riga, Latvia) was alleged to be linked to command-and-control servers for infected botnet computers, as well as being linked to malicious websites, phishing websites and rogue anti-virus products.
Real Host was disconnected by its upstream providers on 1 August 2009. The impact was immediately felt (spam volumes dropped briefly by as much as 38% in the subsequent 48-hour period).
The figure shows the relative proportion of spam originating from the five major botnets globally during the period of this attack: Cutwail, Xarvester, Rustock, Mega-D, and Donbot.
Much of this spam was linked to the Cutwail botnet, currently one of the largest botnets and responsible for approximately 15-20% of all spam. Its activity levels fell by as much as 90% when Real Host was taken offline, but quickly recovered in a matter of days.