Junos OS offers directors with a customized command-line interface (CLI) that enables issuing Junos particular instructions, but additionally the flexibility to change to the underlying FreeBSD shell and use the final FreeBSD command-line instruments and applications.
The OS additionally implements a modified variant of the NetBSD Verified Exec (veriexec), a kernel-based file integrity verification subsystem whose purpose is to guard towards the execution of unauthorized binaries. As such, deploying and operating any malware implant requires a bypass of this function or disabling it fully, which might elevate alerts.
UNC3886 developed a fancy course of injection approach to be able to bypass variexec by making a hung course of utilizing the built-in and bonafide cat utility, writing a malicious shellcode loader to particular reminiscence areas assigned to the cat course of after which tricking the method to execute that code. For the reason that malicious code execution occurred by way of a trusted course of, variexec was bypassed.
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