Dolphin, a sophisticated backdoor discovered by ESET researchers, expands the ScarCruft APT group’s arsenal with a wide range of spying capabilities, including monitoring drives and portable devices and exfiltrating files of interest, keylogging and taking screenshots, and stealing credentials from browsers.
Its functionality is restricted to specific targets, to which the backdoor is deployed following an initial compromise with less sophisticated malware. Dolphin makes extensive use of cloud storage services, particularly Google Drive, for command-and-control communication.
The backdoor can exfiltrate files from a path specified in a command, and it actively searches drives for files with interesting extensions and automatically exfiltrates them. In addition, the backdoor gathers basic information about the targeted machine, such as the operating system version, malware version, list of installed security products, username, and computer name.
Following the deployment of the Dolphin backdoor on selected targets, it searches the drives of compromised systems for interesting files and exfiltrates them to Google Drive. And ESET researchers have observed multiple versions of Dolphin since its initial discovery in April 2021, in which threat actors improved the backdoor’s capabilities and attempted to avoid detection.
Dolphin searches all fixed (HDD) and non-fixed (USB) drives, generates directory listings, and exfiltrates files based on their extension. Dolphin can also search for portable devices like smartphones using the Windows Portable Device API.
The sources for this piece include an article in BleepingComputer.