The implant for Windows is called BothanSpy and targets versions 3,4 and 5 of the SSH client Xshell. It dates back to 2015. The Linux implant is known as Gyrfalcon and is aimed at OpenSSH; it dates back to 2013.
SSH is a program used to log into another computer over a network, to execute commands in a remote machine, and to move files from one machine to another. It provides strong authentication and secure communications over insecure channels.
OpenSSH is a free implementation of SSH developed by the OpenBSD project. It is widely believed to be the most popular SSH client.
The stolen credentials can be exfiltrated to a CIA-controlled server.It is installed as a Shellterm 3.x extension on the target machine.
The manual says that BothanSpy will work only if Xshell is running on the target, and it has active sessions. Else, Xshell will not be storing credential information in the location that BothanSpy is programmed to search.
In what appears to be an attempt at humour, the manual also states that BothanSpy "does not destroy the Death Star, nor does it detect traps laid by The Emperor to destroy Rebel fleets".
In the case of the Linux implant, it can do all that the Windows implant does and also collect full or partial traffic of an OpenSSH session. It is installed using a CIA-developed rootkit called JQC/KitV.
The manual describes Gyrfalcon as a library loaded into the OpenSSH client process address space on Linux platforms. Users are required to have detailed knowledge of the various shells on Linux systems and also be adept at using the command line.
Any prospective attacker is also required to know how to gain root privileges in order to install the implant. However Gyrfalcon itself can be run with user permissions.
The implant runs on older versions of Red Hat Enterprise Linux, Debian, Ubuntu, SUSE and CentOS.
WikiLeaks began dumping the Vault 7 stash on 7 March and claims that it is the biggest ever leak of CIA documents.