After the demise of the Dyreza banking malware, the banking trojan vacuum was quickly filled by the TrickBot malware family. TrickBot is a banking and information stealing trojan which is modular in design and can rapidly expand its functionality by retrieving DLLs from its Command and Control server. This threat is spread most commonly by phishing emails but it also includes network propagation functionality to spread through a victims network by using the Microsoft Windows vulnerability known as EternalRomance. In this blog post, we'll dive into the TrickBot malware, its functionality, modules, and Command and Control communications.
Here at InQuest, YARA is among the many tools we use to perform deep-file inspection, with a fairly extensive rule set. InQuest operates at line speed in very high-traffic networks, so these rules need to be fast.
This blog post is the first in a series discussing YARA performance notes, tips, and hacks.
Emotet is one of the most prevalent malware families in the cybercrime realm in 2018 and with no breakthroughs in identifying the actors or larger infrastructure, at least publicly, it seems poised to stay that way for the time being. The malware is typically delivered to users through phishing campaigns with malicious Word documents containing macros. Once executed, Emotet will often drop an additional malware family such as TrickBot or another information stealer. In the case we will look at today, an Emotet phishing campaign led to the delivery of not just one additional malware family but three; AZORult, IcedID, and TrickBot.
The goal of threat hunting is to proactively identify potential threats that have evaded existing security measures. Over the past several months the use of malicious Excel IQY files to deliver malware has fallen into this category for many organizations and users as a blind spot. Threat actors, both cybercrime and APT, have launched phishing campaigns using this technique to evade common detection methodologies and have left computer network defenders wondering how to catch future occurrences of this technique. Although many of the notable phishing campaigns have similar indicators that one might hunt for, limiting yourself to these will leave your scope narrowed to a limited set of known threats, and when hunting you are looking to identify otherwise unknown threats. In this post, we will review how to leverage YARA signatures in a multi-staged hunting approach to identify indicators of potential malicious activity in these file types. We will cover the IQY file format in both its legitimate and malicious uses, as well as identify common indicators of malicious activity seen in the wild, and how we can broaden those indicators to increase the scope of our threat hunting.