Security researchers have warned that the resurrected Kelihos botnet blasted off the face of the web yesterday is still alive.
Experts not involved in the blasting say the miscreants behind the network of compromised Windows computers are working on their comeback. The zombie PC army was walloped offline in September, they say, yet later resurfaced.
Seculert reports that Kelihos-B, which was distributed as a Facebook worm over recent weeks, is still active and spreading - even after the shutdown attempt by CrowdStrike and Kaspersky Labs this week.
Seculert views this botnet as the undead remnants of Kelihos-B rather than the spawn of a new variant of the malware.
The findings suggest that sink-holing 109,000 backdoored machines infected with the spam-spewing and credential-stealing Kelihos Trojan may not have disabled the entire bot network.
"Very little time passed yesterday [Wednesday] between action being taken against the second Kelihos botnet and the appearance of a new variant said to be spreading via Facebook," commented David Harley, senior research fellow at antivirus biz ESET.
"For the time being, the teams involved in the partial disabling of the Kelihos botnet, have implemented another pretty good temporary fix.
"Sink-holing has twice reduced the effectiveness of Kelihos botnets by effectively disabling and diverting communications from infected machines to a system that is now under the control of the 'good guys'. However, there’s a significant risk that machines that are still infected are also likely to fall prey to a new Kelihos botnet, apart from the risks to currently uninfected machines."
Harley added that the gang are in possession of the Kelihos source code, and can therefore tweak the malware to evade future attempts to neutralise it. ®