The threat actors behind the IcedID Trojan are experimenting with various delivery methods to increase efficiency, including sending malicious messages from web-based contact forms.
First observed in 2017 and also referred to as BokBot, IcedID is a banking Trojan that features a modular design and which is often used in combination with ransomware and RATs, to do more harm than just steal banking credentials.
Recent campaigns featuring the threat have revealed the use of various delivery methods, including the traditional spam or hijacked email chains. Some of the attacks, however, switched to the abuse of contact forms for the delivery of malicious messages.
Over the past month, researchers with various security firms have observed an increase in malicious activity surrounding IcedID, with most of the attacks leveraging hijacked email conversations to send the payload.
While Binary Defense has observed the use of Excel XLS file attachments in such attacks, Trend Micro, security researcher Ali Aqeel, and Microsoft say that the malicious payload in the identified attacks was being delivered as a ZIP archive.
Microsoft, on the other hand, also identified a more unusual delivery method for the malicious file, namely web-based contact forms. If not properly secured, such forms can be abused in various types of attacks, and IcedID’s operators have discovered a novel method of leveraging them.
Specifically, messages are sent to site owners/administrators using such contact forms, typically claiming some sort of infringement, making a legal threat, and providing a link to so-called proof of infringement. The attackers use strong and urgent language to pressure recipients into acting.
The link in the message leads to a sites.google.com page, where the recipient is prompted to sign in with their Google credentials, thus further increasing the sense of legitimacy, but also allowing attackers to bypass detection technologies.
Once the recipient signs in, a malicious ZIP file is automatically downloaded. The archive contains a malicious, heavily obfuscated JavaScript file, which is executed to fetch the IcedID payload, alongside a Cobalt Strike beacon.
“This campaign is not only successful because it takes advantage of legitimate contact form emails, but the message content also passes as something that recipients would expect to receive. This creates a high risk of attackers successfully delivering email to inboxes, thereby allowing for “safe” emails that would otherwise be filtered out into spam folders,” Microsoft notes.
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