2021-01 Security Bulletin: Junos OS: Command injection vulnerability in license-check daemon (CVE-2021-0218)

Product Affected:

This issue affects Junos OS 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2.

Problem:

A command injection vulnerability in the license-check daemon of Juniper Networks Junos OS that may allow a locally authenticated attacker with low privileges to execute commands with root privilege.

license-check is a daemon used to manage licenses in Junos OS. To update licenses, a user executes the command 'request system license update' via the CLI. An attacker with access to this CLI command may be able to exploit the vulnerability.

This issue affects Juniper Networks Junos OS:

17.3 versions prior to 17.3R3-S9;
17.4 versions prior to 17.4R2-S12, 17.4R3-S3;
18.1 versions prior to 18.1R3-S11;
18.2 versions prior to 18.2R3-S6;
18.3 versions prior to 18.3R3-S4;
18.4 versions prior to 18.4R3-S6;
19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S3;
19.2 versions prior to 19.2R3-S1;
19.3 versions prior to 19.3R2-S5, 19.3R3;
19.4 versions prior to 19.4R2-S2, 19.4R3;
20.1 versions prior to 20.1R1-S4, 20.1R2;
20.2 versions prior to 20.2R1-S2, 20.2R2.

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

This issue was discovered during external security research.

This issue has been assigned CVE-2021-0218.

Solution:

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S9, 17.4R2-S12, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R3-S6, 19.1R1-S6, 19.1R2-S2, 19.1R3-S3, 19.2R3-S1, 19.3R2-S5, 19.3R3, 19.4R2-S2, 19.4R3, 20.1R1-S4, 20.1R2, 20.2R1-S2, 20.2R2, 20.3R1, and all subsequent releases.

This issue is being tracked as 1519336.

Workaround:

Use access lists or firewall filters to limit CLI access to the device only from trusted, administrative networks or hosts.

Limit access to the Junos OS CLI to only trusted system administrators.

Restrict access to the 'request system license update' CLI command.

Implementation:

Software releases or updates are available for download at https://www.juniper.net/support/downloads/.

Modification History:

2021-01-13: Initial Publication.

CVSS Score:

7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)

Severity Level:

High

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."

Acknowledgements:

Juniper SIRT would like to acknowledge and thank Hoàng Thạch Nguyễn (d4rkn3ss) of STAR Labs for responsibly reporting this vulnerability.

Knowledge Base