Identified by cybersecurity firm ESET, the newly discovered Ramsay malware appears to have been designed expressly to infiltrate air-gapped devices and networks, which are considered near-impossible to breach.
Having infected a machine, the malware reportedly scrapes Word, PDF and ZIP files, along with other sensitive information, before lying in wait for an opportunity to transport the data out of the closed system.
The practice of air-gapping allows businesses to isolate networks or individual computers from the wider corporate network and also the public Internet.
This most stringent of security measures is used primarily by large enterprises and government entities to safeguard highly sensitive documents, intelligence and intellectual property.
ESET claims to have identified three versions of the Ramsay malware, one built in September and a further two in March, suggesting the operators are delivering frequent iterative improvements.
One version contains a spreader module, which is said to be highly aggressive, capable of infecting portable executables (PE) found on removable storage devices such as USB sticks. Researchers believe this is the mechanism by which the malware is transported onto isolated devices and networks.
It is not yet clear how Ramsay is able to extract data from air-gapped environments, with which the malware operators have no way of communicating remotely.
ESET researcher Ignacio Sanmillan has suggested a hacker might compromise an Internet-connected device used to transfer files to air-gapped systems, which can then be used to perform exfiltration, or else might have physical access to the infected network.
Although the malware has not been formally attributed to a cybercriminal group, Sanmillan believes Ramsay shares common qualities with Retro, a malware strain developed and operated by South Korean syndicate DarkHotel.