It took spam criminals just a bit of time to recover from the takedown of the Grum botnet, one of the largest spam-shooting networks allegedly accountable for one third of all the junk mails wasting Internet bandwidth worldwide. The worst part, experts warn, is that the aforementioned criminals are adapting to new, more subtle ways of doing their dirty deeds.
According to new data from security experts, a month after the Grum takedown spam levels are the same as before: cyber-criminals were able to recover the spam-sending “industry” just after a week from the takedown by easily replacing a network of 100,000 infected computers sending 18 million spam messages on a daily basis.
The “business model” of the Grum botnet (also known as “Tedroo” and “Reddyb”) worked against its chances of survival, experts said: the network was huge so it was targeted easily, and a good part of the many PCs infected with the Grum malware were seemingly already blocked by blacklists and spam filters.
The “post-Grum” spam operations, on the other hand, have become more subtle: the new malicious networks are working in “stealth” mode with a smaller army of zombie-PCs to send junk-mail from, employing a type of threat that is more difficult to oppose for security professionals worldwide.
Source: SecurityWeek.com