If REST API is enabled, the Junos OS login credentials are vulnerable to brute force attacks.

The high default connection limit of the REST API may allow an attacker to brute-force passwords using advanced scripting techniques. Additionally, administrators who do not enforce a strong password policy can increase the likelihood of success from brute force attacks.

Affected releases are Juniper Networks Junos OS:

• 14.1X53 versions prior to 14.1X53-D49;
• 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-D495, 15.1X53-D591, 15.1X53-D69;
• 16.1 versions prior to 16.1R3-S10, 16.1R4-S12, 16.1R6-S6, 16.1R7-S3;
• 16.1X65 versions prior to 16.1X65-D49;
• 16.2 versions prior to 16.2R2-S7;
• 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-S2;
• 17.4 versions prior to 17.4R1-S6, 17.4R2-S2;
• 18.1 versions prior to 18.1R2-S4, 18.1R3-S1;
• 18.2 versions prior to 18.2R1-S5;
• 18.2X75 versions prior to 18.2X75-D30;
• 18.3 versions prior to 18.3R1-S1.

The REST API can be enabled using the following configuration option:

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned  CVE-2019-0039 .
 

The following software releases have been updated to resolve this specific issue: Junos OS 14.1X53-D49, 15.1F6-S12, 15.1R7-S3, 15.1X49-D160, 15.1X53-D236, 15.1X53-D495, 15.1X53-D591, 15.1X53-D69, 16.1R3-S10, 16.1R4-S12, 16.1R6-S6, 16.1R7-S3, 16.1X65-D49, 16.2R2-S7, 17.1R2-S10, 17.1R3, 17.2R1-S8, 17.2R3-S1, 17.3R3-S2, 17.4R1-S6, 17.4R2-S2, 18.1R2-S4, 18.1R3-S1, 18.2R1-S5, 18.2X75-D30, 18.3R1-S1, 18.4R1, and all subsequent releases.

This issue is being tracked as PR  1289313  which is visible on the Customer Support website.

Note: Juniper SIRT's  policy  is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).
 

Software Releases, patches and updates are available at  https://www.juniper.net/support/downloads/ .
 

• Setting a connection limit on REST API may help mitigate this issue.  For example:
   

• Use access lists or firewall filters to limit API access to the device only from trusted hosts.
   

• 2019-04-10: Initial Publication
   

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process. [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team