A vulnerability in OpenSSH may allow a remote network based attacker to effectively bypass restrictions on number of authentication attempts, as defined by MaxAuthTries settings on Junos. This may enable brute force password attacks to gain access to the device. Background: The PAM (Pluggable Authentication Modules) library provides a flexible framework for user authentication and session setup / teardown. It is used not only in the base system, but also by a large number of third-party applications. Various authentication methods (UNIX, LDAP, Kerberos etc.) are implemented in modules which are loaded and executed according to predefined, named policies. These policies are defined in /etc/pam.conf, /etc/pam.d/ <policy name> , /usr/local/etc/pam.conf or /usr/local/etc/pam.d/ <policy name> . The PAM API is a de facto industry standard which has been implemented by several parties. FreeBSD uses the OpenPAM implementation. This issue is assigned CVE-2015-5600.
The following software releases have been updated to resolve this specific issue: Junos OS 12.1X44-D55, 12.1X46-D40, 12.1X47-D30*, 12.3R11, 12.3X48-D20*, 13.2X51-D40*, 13.2X52-D30, 13.3R8, 14.1R6, 14.2R5, 15.1F3, 15.1F2-S1, 15.1R2, 15.1X49-D20, 15.1X53-D20, and all subsequent releases. * upcoming releases . This issue is being tracked as PR 1106752 and is visible on the Customer Support website. KB16765 [juniper.net] - "In which releases are vulnerabilities fixed?" describes which release vulnerabilities are fixed as per our End of Engineering and End of Life support policies.
As a workaround, use access lists or firewall filters to limit access to the device, so that it can only be accessed from trusted hosts. Restrict access to only highly trusted administrators. Additionally, system administrators may disable password based authentication completely, and implement key based authentication exclusively in their SSH server configuration. This would eliminate the possibility of being ever exposed to password brute force attacks.
2015-10-14: Initial publication