CVE-2021-31350 : What You Need to Know

An Improper Privilege Management vulnerability in the gRPC framework used by the Juniper Extension Toolkit (JET) API on Juniper Networks Junos OS and Junos OS Evolved has been identified. This vulnerability enables a low-privileged authenticated attacker to execute operations as root, potentially compromising the entire system.

Understanding CVE-2021-31350

This section provides insights into the nature of the vulnerability, its impacts, technical details, and mitigation strategies.

What is CVE-2021-31350?

The CVE-2021-31350 vulnerability arises due to improper privilege management within the gRPC framework, specifically affecting the JET API on Juniper Networks Junos OS and Junos OS Evolved. By exploiting this vulnerability, a network-based, low-privileged attacker can leverage root-level access, leading to the complete compromise of the targeted system.

The Impact of CVE-2021-31350

The impact of this vulnerability is severe, as it allows an attacker to perform operations as root, compromising the integrity, confidentiality, and availability of the system. This issue could potentially result in a full system takeover.

Technical Details of CVE-2021-31350

In-depth technical information regarding the vulnerability, affected systems, and exploitation mechanisms are discussed below.

Vulnerability Description

The vulnerability enables a low-privileged authenticated attacker to execute operations as root on Juniper Networks Junos OS and Junos OS Evolved systems. This privilege escalation occurs due to the JET service daemon authenticating the user and passing configuration operations directly to the root-level management daemon.

Affected Systems and Versions

Juniper Networks Junos OS versions 18.4 and above, along with Junos OS Evolved prior to version 20.4R2-EVO, are susceptible to this privilege escalation vulnerability.

Exploitation Mechanism

The vulnerability allows a low-privileged attacker to bypass normal access controls and perform operations as a root user, compromising the entire system in the process.

Mitigation and Prevention

This section outlines immediate steps to secure systems and prevent potential exploitation of CVE-2021-31350.

Immediate Steps to Take

Implement access lists or firewall filters to restrict gRPC access to the device from trusted hosts and authorized administrators.

Long-Term Security Practices

Regularly update and patch Juniper Networks Junos OS and Junos OS Evolved to the latest recommended versions to mitigate this vulnerability effectively.

Patching and Updates

Juniper Networks has released software updates to address the CVE-2021-31350 vulnerability. Ensure that affected systems are updated to the following versions:

Junos OS: 18.4R1-S8, 18.4R2-S8, 18.4R3-S8, 19.1R2-S3, 19.1R3-S5, 19.2R1-S7, 19.2R3-S2, 19.3R2-S6, 19.3R3-S2, 19.4R1-S4, 19.4R2-S4, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R2-S3, 20.2R3, 20.3R2-S1, 20.3R3, 20.4R2, 21.1R1, and all subsequent releases.
Junos OS Evolved: 20.4R2-EVO, 21.1R2-EVO, 21.2R1-EVO, and all subsequent releases.