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CVE-2021-21279 : Exploit Details and Defense Strategies

Learn about CVE-2021-21279, a high-severity vulnerability in Contiki-NG OS versions prior to 4.6, allowing attackers to trigger an infinite loop via IPv6 neighbor solicitation messages.

This article provides an overview of CVE-2021-21279, which involves an infinite loop vulnerability in the processing of IPv6 neighbor solicitation in Contiki-NG OS versions prior to 4.6.

Understanding CVE-2021-21279

CVE-2021-21279 is a security vulnerability in Contiki-NG, an open-source operating system designed for IoT devices. The flaw allows an attacker to trigger an infinite loop in the processing of IPv6 neighbor solicitation messages, potentially leading to a denial-of-service attack.

What is CVE-2021-21279?

In Contiki-NG versions earlier than 4.6, an attacker can exploit an infinite loop issue in the handling of IPv6 neighbor solicitation messages. This attack can disrupt the system's operation due to the cooperative scheduling mechanisms used in Contiki-NG's core components and communication stack.

The Impact of CVE-2021-21279

The vulnerability has a CVSS v3.1 base score of 7.5, indicating a high severity issue. It can result in a denial-of-service condition, affecting the availability of IoT devices running the affected Contiki-NG versions. The flaw does not impact confidentiality or integrity but can lead to system unresponsiveness.

Technical Details of CVE-2021-21279

CVE-2021-21279 is classified under CWE-835, denoting a 'Loop with Unreachable Exit Condition.' Here are some technical details regarding this vulnerability:

Vulnerability Description

The vulnerability arises from a flaw in handling IPv6 neighbor solicitation messages, allowing an attacker to trigger an infinite loop, disrupting normal system operation.

Affected Systems and Versions

Contiki-NG versions prior to 4.6 are impacted by this vulnerability, exposing devices running the outdated OS to potential denial-of-service attacks.

Exploitation Mechanism

Attackers can exploit this vulnerability by sending crafted IPv6 neighbor solicitation messages to the target device, causing it to enter an infinite loop state and resulting in a denial-of-service condition.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-21279, users and administrators are advised to take the following actions:

Immediate Steps to Take

        Update Contiki-NG installations to version 4.6 or later to apply the necessary patches that address this vulnerability.
        Implement network-level protections to filter out malicious IPv6 neighbor solicitation messages.

Long-Term Security Practices

        Regularly monitor for security advisories and updates from Contiki-NG to stay informed about potential vulnerabilities.
        Follow secure coding practices to minimize the impact of similar issues in IoT deployments.

Patching and Updates

        Ensure that all IoT devices running Contiki-NG are promptly patched with the latest updates to prevent exploitation of known vulnerabilities.

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