One man may be under arrest and the worst of the attacks curtailed by law enforcement authorities, but researchers say it’s still too early to suggest Dridex, a botnet spawned by the Cridex Trojan, has been completely neutralized.

Several security vendors involved in the recent operation to take down Dridex told SecurityWeek that spam featuring the Trojan was discovered less than two days after it was initially shut down. Though smaller than the original Dridex, which has reportedly led to more than $40 million in losses so far, this sub-botnet is aimed at users in the U.K. These recent discoveries suggested the work to eradicate it completely is far from over.

For those still getting caught up, The Guardian has published an in-depth FAQ about Dridex, including its origins from the Cridex Trojan and the way it spreads via email and triggers malicious macros in Microsoft Word documents. By stealing login credentials and other personal information, experts claimed Dridex has been allowing cybercriminals from a collective known as Evil Corp. to target a wide range of organizations.

Last week, however, The Register and other publications said the so-called command-and-control malware factory suffered a significant setback when the FBI arrested a Moldovan man named Andrey Ghinkul and seized multiple servers believed to have been involved in using the Trojan. More than likely, Ghinkul is but one member of Evil Corp., and his extradition and prosecution in the U.S. will only be the first step in an ongoing attempt to fend off further attacks.

In fact, a public statement posted by the U.S. Department of Justice (DOJ) said the FBI is working with at least 12 different agencies and vendors as part of its investigation into Dridex. This reflects just how global threats such as banking Trojans have become, and it underscores the increasing challenge of making sure the tools enabling such cybercriminal activity aren’t simply picked up by someone else after initial arrests are made.

In the meantime, the DOJ statement said those who think they might be infected can remove the botnet by visiting a link on the U.S. Computer Emergency Readiness Team (US-CERT) site.