Junos OS: 'set system ports console insecure' allows root password recovery on OAM volumes

Summary

When "set system ports console insecure" is enabled, root login is disallowed for Junos OS as expected. However, the root password can be changed using "set system root-authentication plain-text-password" on systems booted from an OAM (Operations, Administration, and Maintenance) volume, leading to a possible administrative bypass with physical access to the console. OAM volumes (e.g. flash drives) are typically instantiated as /dev/gpt/oam, or /oam for short. Password recovery, changing the root password from a console, should not have been allowed from an insecure console. Affected releases are Juniper Networks Junos OS: 15.1 versions prior to 15.1F6-S12, 15.1R7-S3; 15.1X49 versions prior to 15.1X49-D160; 15.1X53 versions prior to 15.1X53-D236, 15.1X53-D496, 15.1X53-D68; 16.1 versions prior to 16.1R3-S10, 16.1R6-S6, 16.1R7-S3; 16.1X65 versions prior to 16.1X65-D49; 16.2 versions prior to 16.2R2-S8; 17.1 versions prior to 17.1R2-S10, 17.1R3; 17.2 versions prior to 17.2R1-S8, 17.2R3-S1; 17.3 versions prior to 17.3R3-S3; 17.4 versions prior to 17.4R1-S6, 17.4R2-S2; 18.1 versions prior to 18.1R2-S4, 18.1R3-S3; 18.2 versions prior to 18.2R2; 18.2X75 versions prior to 18.2X75-D40; 18.3 versions prior to 18.3R1-S2. This issue does not affect Junos OS releases prior to 15.1.