CVE-2021-0244 : Exploit Details and Defense Strategies
Discover how CVE-2021-0244 in Juniper Networks Junos OS could allow attackers to bypass storm control features, leading to a Denial of Service condition. Learn about affected systems and recommended mitigation strategies.
A signal handler race condition in the Layer 2 Address Learning Daemon (L2ALD) of Juniper Networks Junos OS may allow an attacker to bypass storm control on devices, leading to a Denial of Service condition. The issue affects various Junos OS versions.
Understanding CVE-2021-0244
This CVE describes a vulnerability in Juniper Networks Junos OS that could be exploited by an attacker to cause a Denial of Service condition by bypassing the storm control feature.
What is CVE-2021-0244?
A signal handler race condition exists in Junos OS due to the absence of a protection mechanism, allowing an attacker to bypass storm control features, potentially resulting in a Denial of Service attack.
The Impact of CVE-2021-0244
This vulnerability, if exploited, can lead to a Denial of Service (DoS) condition on affected devices, affecting network availability.
Technical Details of CVE-2021-0244
Vulnerability Description
The vulnerability arises from a race condition in L2ALD, triggered by specific actions taken by an administrator on devices, especially those configured in Virtual Chassis configurations.
Affected Systems and Versions
Juniper Networks Junos OS versions 14.1X53 to 19.1 are affected before the specified patch versions on EX Series and SRX Series.
Exploitation Mechanism
The absence of a specific protection mechanism allows an attacker to exploit the race condition and bypass the storm control feature on Junos OS devices.
Mitigation and Prevention
Immediate Steps to Take
There are no viable workarounds other than rebooting the device and monitoring for indicators of compromise (IoC). Clearing the IoC from log files is essential to prevent exploitation.
Long-Term Security Practices
Ensure devices are updated with the patched software releases provided by Juniper Networks to mitigate the vulnerability effectively.
Patching and Updates
Refer to Juniper's Security Services Administration Guide for detailed information on safeguarding against this vulnerability.