High-performance computer networks, some belonging to the world’s most prominent organizations, are under attack by a newly discovered backdoor that gives hackers the ability to remotely execute commands of their choice, researchers said on Tuesday.

Kobalos, as researchers from security firm Eset have named the malware, is a backdoor that runs on Linux, FreeBSD, and Solaris, and code artifacts suggest it may have once run on AIX and the ancient Windows 3.11 and Windows 95 platforms. The backdoor was released into the wild no later than 2019, and the group behind it was active throughout last year.

Multistriped backdoor

While the Kobalos design is complex, its functionalities are limited and almost entirely related to covert backdoor access. Once fully deployed, the malware gives access to the file system of the compromised system and enables access to a remote terminal that gives the attackers the ability to run arbitrary commands.