At the start of 2021, a Europol and Eurojust-led operation involving law enforcement agencies in 8 countries successfully took down the infamous Emotet botnet. The botnet consisted of an estimated 1.6 million devices worldwide that had been infected with the Emotet Trojan.
The Emotet Trojan first appeared in 2014 and was originally a banking trojan, although it evolved into a malware downloader that was rented out to cybercrime gangs under the malware-as-a-service model. The botnet was used to give those threat actors a foothold in victims’ environments and allowed them to install malware such as IcedID, QakBot, and TrickBot. Those malware variants were then used to deliver ransomware such as Conti and Ryuk.
Emotet posed a massive threat to businesses worldwide prior to its takedown. In addition to being a malware distribution tool, the botnet was used to launch Distributed Denial of Service (DDoS) attacks and large-scale spamming campaigns against high-profile targets around the world.
The Emotet botnet was controlled by a network of hundreds of servers worldwide. The takedown, which occurred on January 27, 2021, saw its infrastructure taken over by law enforcement. On April 25, 2021, law enforcement in Germany launched a cleanup operation that added a module that removed the Emotet Trojan from victims’ systems. 2 individuals were arrested who were suspected of involvement in maintaining the botnet, and in the weeks and months that followed no Emotet activity was detected. However, that has now changed.
The Emotet Botnet is Back
Law enforcement took control of the command-and-control infrastructure of Emotet and removed the Emotet Trojan from all infected devices, and while that was sufficient to kill the botnet, it was not enough to prevent its return. Researchers at GData, Advanced Intel, and Cryptolaemus have all discovered instances where the TrickBot Trojan has delivered an Emotet loader.
The Emotet botnet operators have previously worked with the threat actors behind the Trickbot Trojan, using their botnet to grow the TrickBot botnet. That process is now happening in reverse. A new version of the loader and Emotet Trojan have been created and it appears that the Emotet botnet is being reconstructed from scratch.
At this stage, there are relatively few devices infected with Emotet but that is not likely to remain the case for long. Around 246 devices are known to have had the Emotet Trojan installed, and they are being used as its command-and-control infrastructure at present.
Emotet was known for conducting malspam campaigns to grow the botnet, and spamming campaigns have already been detected using several different lures and a variety of attachments. Spam emails spreading Emotet have used Word files and Excel spreadsheets with malicious macros, and to prevent analysis by email security solutions, some emails have used password-protected zip files. Some of the lures detected by security researchers in the first campaigns include notifications about canceled dental insurance, Cyber Monday and Black Friday sales, notifications about canceled meetings, and requests for political party donations.
How to Protect Against Infection with Emotet
Protecting against Emotet involves implementing measures that also protect against TrickBot infections. Since both Emotet and TrickBot are extensively delivered via malspam emails, implementing an advanced email security solution is a good place to start.
One of the most effective tactics used by the Emotet gang was hijacking message threads. This involves sending replies to previous message conversations and adding a malicious hyperlink or infected email attachment. Since the messages were sent from email accounts known to the recipient, links were often clicked, and attachments opened.
Security awareness training often teaches employees to be suspicious of unsolicited messages from unknown individuals. It is important to make employees aware that malicious emails may also come from known individuals and to warn employees that hijacked message threads are used to deliver malware. Security awareness training can be effective, but it is nowhere near as effective as technical solutions that block malicious messages.
Security can be improved by choosing an email security solution with outbound email scanning. This feature will scan outgoing messages to detect compromised email accounts, allowing security teams to take prompt action to isolate infected devices. You should also ensure that your email security solution includes sandboxing in addition to antivirus engines, as the latter can only detect known malware variants. Attachments that pass standard AV scans are sent to an email sandbox where they are subjected to in-depth analysis to identify malicious actions.
These features and many more are included in SpamTitan from TitanHQ. SpamTitan is effective at blocking the full range of email-based threats and is easy to implement and use. If you want to improve your defenses against dangerous email threats such as TrickBot, IcedID, QakBot, and Emotet without breaking the bank, give the TitanHQ team a call for more information about SpamTitan.
SpamTitan is available on a free trial and product demonstrations can be arranged on request.