The Iranian state-sponsored cyber espionage group, OilRig, has been identified deploying three new malware downloaders named ODAgent, OilCheck, and OilBooster throughout 2022 to maintain persistent access to victim organizations in Israel. Slovak cybersecurity company ESET uncovered these lightweight downloaders, notable for using legitimate cloud service APIs such as Microsoft Graph OneDrive and Outlook APIs for command-and-control communication.
This approach helps the threat actor blend with authentic network traffic and conceal their attack infrastructure. The targets of the campaign include organizations in the healthcare sector, manufacturing, and local government, with all victims having been previously targeted by the OilRig group. OilRig, also known as APT34, has been active since at least 2014, employing various malware to target entities in the Middle East. In 2023, the group was observed using novel malware like MrPerfectionManager, PowerExchange, Solar, Mango, and Menorah.
ODAgent, detected in February 2022, is a C#/.NET downloader utilizing the Microsoft OneDrive API for command-and-control communications, while SampleCheck5000 interacts with a shared Microsoft Exchange mail account to download and execute additional OilRig tools. OilBooster and OilCheck also leverage Microsoft OneDrive API and Microsoft Graph API, respectively, for command-and-control communication, with the former interacting with an actor-controlled OneDrive account. These downloaders share similarities with other OilRig tools in using email-based C2 protocols to exchange messages with the operators, emphasizing the use of a shared OilRig-operated account across multiple victims.
