In late July 2024, we detected a series of ongoing targeted cyberattacks on dozens of computers at Russian government organizations and IT companies. The threat actors infected devices using phishing emails with malicious shortcut attachments. These shortcuts were used to deliver malware that received commands via the Dropbox cloud service. Attackers used this malware to download additional payloads onto infected computers, in particular tools used by the APT31 group and an updated CloudSorcerer backdoor. We dubbed this campaign EastWind.
Below are the most interesting facts about the implants used in this campaign:
The malware downloaded by the attackers from Dropbox has been used by APT31 since at least 2021. We named it GrewApacha.
The attackers updated the The CloudSorcerer backdoor (described by us in early July 2024) ) after we published our blogpost. It currently uses LiveJournal (a social network popular in Russia) and Quora profiles as initial C2 servers.
The attacks additionally deploy a previously unknown implant with a classic backdoor functionality, which we dubbed PlugY. It is loaded via the CloudSorcerer backdoor, and its command set is quite extensive. It supports three different protocols for communicating with C2, and what’s more, its code resembles that of the DRBControl backdoor (aka Clambling), which several companies attribute to the APT27 group.
Technical information
As mentioned above, the attackers used spear phishing to gain an initial foothold into the organizations. They sent malicious emails with attached RAR archives to target organizational em ..
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