Impact on Cutwail of 3FN shutdown

The CBL report documents a sharp decline in spam sent by the Cutwail/Cutwail2 botnets following the June 2009 shutdown of a major C&C hosting provider (3FN). Cutwail2 temporarily dropped to zero for extended intervals and later recovered to roughly a quarter of prior volumes as new C&C servers appeared, illustrating that targeted takedowns can markedly reduce spam but may not permanently eliminate botnet activity.