In the November SpamRankings.net from PSBL data, Global Crossing’s AS 3549 GBLX spiked on 17 November and a few days before, pushing it into fifth place.

Did this spam spike come from any particular botnet?

AS 3549 GBLX PSBL spam volume left axis, CBL botnet volume right axis It looks like GBLX is infested with many botnets, but the spike on 17 Nov roughly corresponds with a cutwail botnet volume peak on 16 Nov. Given that the ASN volume spike is from PSBL data and the botnet volume peak is from CBL data, a day off is plausible, due to different collection and delivery times.

There’s also a peak for grum (green line near the bottom) on 17 Nov, and peaks for festi and n/a on 18 Nov, where n/a is CBL’s marker for spam they detected without having to look as far as determining which botnet they think sent it.

So the spam spike could be from cutwail. Or it could be because of a coincidence of several botnet peaks. Or it could be some other botnet that happened to do a spam campaign on that day. Given that the PSBL GBLX peak builds up on 16 Nov, I’d guess it came mostly from cutwail.

We could try to resolve this question by digging into the specific addresses the GBLX spam PSBL saw came from and see if they match addresses CBL assigned to botnets.

-jsq