June 17, 2020 By Threat Intelligence Team
This blog post was authored by Hossein Jazi and Jérôme Segura
On June 10, we found a malicious Word document disguised as a resume that uses template injection to drop a .Net Loader. This is the first part of a multi-stage attack that we believe is associated to an APT attack. In the last stage, the threat actors used Cobalt Strike’s Malleable C2 feature to download the final payload and perform C2 communications.
This attack is particularly clever for its evasion techniques. For instance, we observed an intentional delay in executing the payload from the malicious Word macro. The goal is not to compromise the victim right away, but instead to wait until they restart their machine. Additionally, by hiding shellcode within an innocuous JavaScript and loading it without touching the disk, this APT group can further thwart detection from security products.