Two weeks after service warnings are published better safetys from France, Japan and New Zealand on increasing Emotet activity, new warnings were published in Italy the Netherlands, but also from Microsoft.
These new alerts come as Emotet activity continues to grow, overshadowing any other malware activity that is active today.
Emotet is by far the largest malware botnet. It was dormant for most of this year, from February to July, but apparently came back for good.
Unfortunately, the inactivity didn't last long, and Emotet's operators are back in full control of their botnet, which they're using to send more and more spam. messages.
These spam emails come with malicious files, which infect the host with the Emotet malware. The gang soon after sells her access on these infected hosts to other gangs of ransomware administrators
Many times, and especially in large corporate environments, an Emotet infection can turn into an ransomware attack within a few hours.
This is why cyber security services and CERT teams in France, Japan, New Zealand, Italy and the Netherlands are so scared of Emotet spam campaigns and issue defense-boosting alerts.
Emotet currently prefers to use one techniques called “email chains” or “hijacked treads.”
For the technique used by the Emotet gang, it first steals an existing email chain from an infected host and then responds to emails using the existing subject. The spy email comes with a forged ID, and contains a malicious document, hoping to trick the email chain participants into opening the attachment and infecting their system.
Emotet has been using this technique since October 2018 but has improved it a lot lately.
The technique is quite clever and effective and has been analyzed in a published report today by Palo Alto Networks.
However, the notices from Microsoft and Italian authorities also warn of another recent change in Emotet's spam campaigns, which now also use ZIP files protected with code instead of Office documents.
The idea is that by using such password-protected files, email security portals cannot open it archive to scan its contents and won't see any traces of malware it contains.
Emotet joined the password-protected attachment bandwagon with a campaign starting Friday. The campaign slowed down over the weekend (typical of Emotet) but was back today in even larger volumes of emails in English, as well as in some European languages. pic.twitter.com/POppQ51uMX
— Microsoft Threat Intelligence (@MsftSecIntel) September 22, 2020