ScreenOS is a real-time embedded operating system for the NetScreen range of hardware firewall devices from Juniper Networks.
Beside transport level security ScreenOS also integrates these flow management applications: In December 2015, Juniper Networks announced that it had found unauthorized code in ScreenOS that had been there since August 2012.
The two backdoors it created would allow sophisticated hackers to control the firewall of un-patched Juniper Netscreen products and decrypt network traffic.
[2] Many in the security industry praised Juniper for being transparent about the breach.
The exploit capabilities seem consistent with the program codenamed FEEDTROUGH.