In a coordinated action, multiple law enforcement agencies have seized control of the Emotet botnet. Agencies from eight countries worked together to deliver what they hope will be a decisive blow against one of the world's most dangerous and sophisticated computer security threats.
The Emotet threat
In a statement announcing the action, Europol described Emotet as "one of the most significant botnets of the past decade" and the world's "most dangerous" malware.
The malware has been a significant thorn in the side of victims, malware researchers and law enforcement since it first emerged in 2014. Originally designed as a banking Trojan, the software became notorious for its frequent shapeshifting and its ability to cause problems for people trying to detect it. This lead to it being used as a gateway for other kinds of malware. Emotet's criminal operators succeeded in infiltrating millions of Windows machines, and then sold access to those machines to other malware operators.
Taking down Emotet's infrastructure not only hobbles Emotet, it also disrupts an important pillar of the malware delivery ecosystem.
Successful botnets are typically highly distributed and very resilient to takedown attempts. Effective law enforcement cooperation is therefore vital, so that all parts of the system are tackled at the same time, ensuring the botnet can't reemerge from any remnants that go untouched.
In this case, that meant tackling hundreds of servers simultaneously. Describing the level of cooperation required, Malwarebytes' Director of Threat Intelligence, Jerome Segura said:
Going after any botnet is always a challenging task, but the stakes were even higher with Emotet. Law Enforcement agencies had to neutralize Emotet's three different botnets and their respective controllers.
Although it gives few details, the Europol press release hints that a novel and sophisticated approach was used in the action, stating that the Emotet botnet was compromised "from the inside". According to the agency, "This is a unique and new approach to effectively disrupt the activities of the facilitators of cybercrime."
Unlike the recent and short-lived attempt to take down TrickBot, authorities have made actual arrests in Ukraine and have also identified several other individuals that were customers of the Emotet botnet. This is a very impactful action that likely will result in the prolonged success of this global takedown.
It remains to be seen if this is the final chapter of the Emotet story, but even if it is, we aren't at the end of the story just yet.
This action removes the threat posed by Emotet, by preventing it from contacting the infrastructure it uses to update itself and deliver malware. However, the infections remain, albeit in an inert state. To complete the eradication of Emotet, those infections will need to be cleaned up too.
In a highly unusual step, it looks as if the clean up isn't going to be left to chance. A few hours after the takedown was announced, ZDNet broke the news that law enforcement in the Netherlands are in the process of deploying an Emotet update, and that will remove any remaining infections on March 25th, 2021.
Malwarebyes Threat Intelligence has since pointed out that the actual removal date is April 25th, 2021, because, as any programmer can tell you, the first item in an array is zero, not one.