CVE-2021-0227 : Vulnerability Insights and Analysis

An improper restriction of operations within the bounds of a memory buffer vulnerability in Juniper Networks Junos OS J-Web on SRX Series devices allows an attacker to cause Denial of Service (DoS) by sending certain crafted HTTP packets. This can lead to a sustained DoS condition affecting web-management, NTP daemon (ntpd), and Layer 2 Control Protocol process (L2CPD) daemons on various Junos OS versions.

Understanding CVE-2021-20657

This CVE highlights a vulnerability in Juniper Networks Junos OS impacting the SRX Series devices, potentially leading to Denial of Service attacks.

What is CVE-2021-20657?

An improper restriction of operations within the bounds of a memory buffer vulnerability in Juniper Networks Junos OS J-Web on SRX Series devices allows an attacker to cause Denial of Service (DoS) by sending certain crafted HTTP packets. Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition.

The Impact of CVE-2021-20657

When exploited, this vulnerability can result in a sustained Denial of Service (DoS) by crashing web-management, NTP daemon (ntpd), and Layer 2 Control Protocol process (L2CPD) daemons on affected Junos OS versions.

Technical Details of CVE-2021-20657

This section provides deeper insights into the vulnerability, affected systems, and how the exploitation can occur.

Vulnerability Description

The vulnerability involves an improper restriction of operations within a memory buffer, allowing attackers to disrupt services through crafted HTTP packets.

Affected Systems and Versions

Juniper Networks Junos OS on SRX Series devices versions prior to 20.1R2 are affected, with various subversions listed in the advisory.

Exploitation Mechanism

Attackers can exploit this vulnerability by sending specially crafted HTTP packets to targeted devices, triggering a sustained Denial of Service (DoS) condition.

Mitigation and Prevention

Understanding the immediate steps and long-term practices to mitigate the impact of CVE-2021-20657.

Immediate Steps to Take

Apply the provided software updates for Junos OS versions to address this vulnerability and prevent potential DoS attacks.

Long-Term Security Practices

To reduce the risk of exploitation, limit network access to trusted administrative hosts using access lists or firewall filters.

Patching and Updates

Ensure that the Junos OS software is regularly updated to the latest recommended releases to patch security vulnerabilities.