CVE-2021-31359 : Exploit Details and Defense Strategies

A local privilege escalation vulnerability in Juniper Networks Junos OS and Junos OS Evolved allows a local, low-privileged user to cause the Juniper DHCP daemon (jdhcpd) process to crash, resulting in a Denial of Service (DoS), or execute arbitrary commands as root. This issue affects multiple versions of Junos OS and Junos OS Evolved.

Understanding CVE-2021-31359

This CVE identifies a severe local privilege escalation vulnerability in Juniper Networks Junos OS and Junos OS Evolved that can lead to system crashes and potential unauthorized command execution.

What is CVE-2021-31359?

CVE-2021-31359 is a vulnerability in Junos OS and Junos OS Evolved that allows a local, low-privileged user to crash the DHCP daemon process, leading to a DoS condition or possible execution of arbitrary commands as root.

The Impact of CVE-2021-31359

The vulnerability poses a high risk as it can be exploited by a local user to disrupt services, crash systems, and potentially gain unauthorized access as a root user.

Technical Details of CVE-2021-31359

The vulnerability is categorized with a CVSS base score of 7.8 (High severity) due to its low attack complexity, local attack vector, and high impact on confidentiality, integrity, and availability.

Vulnerability Description

The flaw enables a local attacker to crash the jdhcpd process, leading to a DoS condition or execution of arbitrary commands with elevated privileges.

Affected Systems and Versions

Junos OS versions prior to 21.2R1, including several specific releases, and all versions of Junos OS Evolved prior to 21.2R1 are affected by this vulnerability.

Exploitation Mechanism

While there are no known instances of malicious exploitation, attackers can leverage this vulnerability to disrupt network services and potentially escalate privileges.

Mitigation and Prevention

Immediate actions and long-term security practices are essential to mitigate the risks associated with CVE-2021-31359.

Immediate Steps to Take

Update affected Junos OS and Junos OS Evolved versions to the provided patched releases to address the vulnerability.

Long-Term Security Practices

Implement access lists or firewall filters to restrict access to devices via CLI only from trusted hosts and administrators to prevent unauthorized access.

Patching and Updates

Juniper Networks has released patched software versions for Junos OS and Junos OS Evolved to address this vulnerability.