CVE-2021-0255 : What You Need to Know

A local privilege escalation vulnerability in ethtraceroute of Juniper Networks Junos OS may allow a locally authenticated user with shell access to escalate privileges and write to the local filesystem as root. This vulnerability affects multiple versions of Junos OS.

Understanding CVE-2021-0255

This CVE identifies a critical local privilege escalation vulnerability in Juniper Networks Junos OS that enables authenticated users to gain root access through the ethtraceroute utility.

What is CVE-2021-0255?

The vulnerability in ethtraceroute allows local users with shell access to execute commands with root privileges, potentially leading to unauthorized write access to the local filesystem.

The Impact of CVE-2021-0255

With a CVSS base score of 5.5 (Medium Severity), this vulnerability poses a significant threat to the integrity of affected systems by allowing unauthorized users to escalate their privileges.

Technical Details of CVE-2021-0255

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerability enables local users to exploit the ethtraceroute utility in Junos OS to gain root access and write to the local filesystem.

Affected Systems and Versions

Juniper Networks Junos OS versions prior to the following are affected: 15.1X49-D240, 17.3R3-S11, 17.4R3-S4, 18.1R3-S12, 18.2R3-S7, 18.3R3-S4, 18.4R2-S7, 19.1R1-S6, 19.1R2-S2, 19.1R3-S4, 19.3R3-S2, 19.4R3-S1, 20.1R2, 20.1R3, 20.2R2-S1, 20.2R3, 20.3R1-S1.

Exploitation Mechanism

As per Juniper SIRT, there have been no reports of malicious exploitation of this vulnerability to date.

Mitigation and Prevention

To protect your systems from this vulnerability, follow the recommended mitigation steps.

Immediate Steps to Take

Limit CLI access to trusted networks, apply access lists or firewall filters, and restrict Junos OS shell access to authorized administrators to minimize the risk of exploitation.

Long-Term Security Practices

Regularly update Junos OS to the patched versions mentioned earlier to eliminate the vulnerability and enhance system security.

Patching and Updates

Juniper Networks has released updated software versions to address this specific issue. Install the following releases or any subsequent versions: 15.1X49-D240, 17.3R3-S11, 17.4R3-S4, 18.1R3-S12, 18.2R3-S7, 18.4R2-S7, 19.1R1-S6, 19.1R2-S2, 19.1R3-S4, 19.3R3-S2, 19.4R3-S1, 20.1R2, 20.1R3, 20.2R2-S1, 20.2R3, 20.3R1-S1, 21.1R1, and newer releases.