Hornetsecurity Blog

You should only open email attachments and links from senders you know is an advice often given when it comes to preventing email-based malware and phishing attacks. However, in this article we outline an attack technique called email conversation thread hijacking, which uses victim’s existing email conversations and thus trust-relationships to spread to new victims. Against this attack the previous advice will not help. We explain how email conversation thread hijacking is used by attackers, and why it dramatically increases the likelihood for victims to open malicious links or malicious attachments.

The Hornetsecurity Security Lab observed a 1000 % increase in downloads of the Emotet loader. The increase in Emotet loader downloads correlates with Emotet’s packer change, which causes the Emotet loader to be less detected by AV software. Our gathered data suggests that the increase in Emotet loader downloads stems from the loader being detected less and thus also the Emotet loader download URLs being blocked less by security mechanisms. Our data, however, also suggests that AV vendors are already closing the detection gap and the detection of the Emotet loader should increase again and thus the number of downloads decreasing again. This analysis is a good display of the impact of the changes to the Emotet loader’s packer.

Around 300 billion e-mails are sent every day - the number of e-mails sent and received for private and business purposes is forecast to rise to 361.6 billion by 2024. However, not all e-mails that end up in users' inboxes are wanted, and unwanted e-mails not only...

The Hornetsecurity Security Lab presents details on the webshells behind the Emotet distribution operation, including insights into payload downloads and how from 2020-07-22 to 2020-07-24 Emotet payloads on Emotet download URLs were replaced with HTML code displaying GIFs. The analysis shows that the number of downloads of the malicious content behind the Emotet download URLs is significant and has been observed peaking at 50,000 downloads per hour. Highlighting that Emotet emails do get clicked. The analysis further shows that compromised websites are not just compromised once but multiple times by different actors and cleanup efforts by the website administrators are often insufficient leading to re-enabling of the malicious Emotet downloads.

+++ INFORMATION +++ Currently, it is recommended that affected data flows be identified and switched to alternatives that meet the required level of protection under GDPR. We would therefore like to assure you that Hornetsecurity's cloud email security services are...