2019-04 Security Bulletin: Junos OS: Login credentials are vulnerable to brute force attacks through the REST API (CVE-2019-0039)

Product Affected:

This issue affects Junos OS 14.1X53, 15.1, 15.1X49, 15.1X53, 16.1, 16.1X65, 16.2, 17.1, 17.2, 17.3, 17.4, 18.1, 18.2, 18.2X75, 18.3.

Problem:

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:

system services rest http
system services rest enable-explorer

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.

Solution:

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).

Workaround:

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

set system services rest control connection-limit 100

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

Implementation:

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

Modification History:

2019-04-10: Initial Publication

CVSS Score:

5.3 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)

Severity Level:

Medium

Severity Assessment:

Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Knowledge Base