CVE-2021-0224 : Exploit Details and Defense Strategies

A vulnerability in the handling of internal resources necessary to bring up a large number of Layer 2 broadband remote access subscriber nodes in Juniper Networks Junos OS can lead to a Denial of Service condition due to Access Node Control Protocol daemon crashes.

Understanding CVE-2021-0224

This vulnerability affects Juniper Networks Junos OS across multiple versions, potentially leading to a sustained Denial of Service condition.

What is CVE-2021-0224?

The vulnerability results from a flaw in handling internal resources necessary for establishing a large number of Layer 2 broadband remote access subscriber nodes.

The Impact of CVE-2021-0224

The issue can cause the ANCPD daemon to crash and restart, resulting in a Denial of Service condition, especially when processing spoofed subscriber nodes.

Technical Details of CVE-2021-0224

The vulnerability affects Junos OS versions prior to 17.3R3-S12, with subsequent versions facing varying impacts.

Vulnerability Description

When the number of subscribers trying to connect surpasses the configured maximum-discovery-table-entries value, ANCPD process crashes.

Affected Systems and Versions

All versions of Juniper Networks Junos OS before 17.3R3-S12 are affected, along with subsequent versions up to 20.3R2.

Exploitation Mechanism

Juniper SIRT has not identified any instances of malicious exploitation of this vulnerability.

Mitigation and Prevention

To address CVE-2021-0224, software releases including Junos OS 17.3R3-S12 and beyond have been updated to resolve the issue.

Immediate Steps to Take

Users are advised to update to the patched versions to mitigate the risk of a Denial of Service condition.

Long-Term Security Practices

Maintain regular updates of Junos OS to protect against known vulnerabilities and ensure optimal system security.

Patching and Updates

Apply patches and software updates provided by Juniper Networks to safeguard your systems from potential exploitation.