CVE-2021-0249 : Exploit Details and Defense Strategies

A buffer overflow vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS could allow a remote attacker to execute arbitrary code on an affected device in case UTM services are enabled.

Understanding CVE-2021-0249

This vulnerability affects Juniper Networks Junos OS on SRX Series devices with specific versions. An attacker could exploit this issue through crafted packets to the device.

What is CVE-2021-0249?

The CVE-2021-0249 vulnerability in Juniper Networks Junos OS on SRX Series devices allows remote attackers to execute arbitrary code or commands on the affected device if UTM services are enabled.

The Impact of CVE-2021-0249

With a CVSS base score of 8.1, this high-severity vulnerability could result in unauthorized remote code execution, posing a significant risk to the confidentiality, integrity, and availability of the system.

Technical Details of CVE-2021-0249

This section delves into the specifics of the vulnerability, the affected systems and versions, as well as the exploitation mechanism.

Vulnerability Description

A buffer overflow vulnerability in the PFE of Juniper Networks Junos OS on SRX Series devices with UTM services enabled.

Affected Systems and Versions

SRX Series with Junos OS versions prior to 15.1X49-D190
SRX Series with Junos OS 17.4 versions prior to 17.4R2-S9
SRX Series with Junos OS 17.4R3 and later versions prior to 18.1R3-S9
SRX Series with Junos OS 18.2 versions prior to 18.2R3-S1
SRX Series with Junos OS 18.3 versions prior to 18.3R2-S3, 18.3R3
SRX Series with Junos OS 18.4 versions prior to 18.4R2-S3, 18.4R3
SRX Series with Junos OS 19.1 versions prior to 19.1R1-S4, 19.1R2
SRX Series with Junos OS 19.2 versions prior to 19.2R1-S1, 19.2R2

Exploitation Mechanism

The vulnerability can be exploited by sending crafted packets to the device through UTM services.

Mitigation and Prevention

To protect your systems, consider the immediate steps, security practices, and patching details outlined below.

Immediate Steps to Take

Update Juniper Networks Junos OS to the patched versions: 15.1X49-D190, 17.4R2-S9, 18.1R3-S9, 18.2R3-S1, 18.3R2-S3, 18.3R3, 18.4R2-S3, 18.4R3, 19.1R1-S4, 19.1R2, 19.2R1-S1, 19.2R2, 19.3R1, or later releases.

Long-Term Security Practices

Regularly update Junos OS and other software to mitigate vulnerabilities.
Implement network segmentation and access controls to limit exposure.

Patching and Updates

Deploy the latest software releases to address the vulnerability and ensure ongoing protection against potential threats.