CVE-2021-27854 is a vulnerability affecting Layer 2 network filtering capabilities, specifically targeting IPv6 Router Advertisement (RA) guard mechanisms. This vulnerability allows for the potential bypass of filtering controls through the use of VLAN 0 headers and LLC/SNAP headers, which can convert frames between Ethernet and Wi-Fi. The impact of this vulnerability is classified as medium severity, with a CVSS score of 4.7.
Organizations utilizing affected systems should recognize the potential risk associated with this vulnerability. Given its medium severity classification, it is crucial for organizations to assess their exposure and prioritize remediation efforts accordingly.
As of now, there are no known exploits publicly available for this vulnerability, and it has not been included in the Known Exploited Vulnerabilities (KEV) catalog. However, organizations should not dismiss the potential for future exploitation.
To mitigate the associated risks, organizations should prioritize patching and updates to their network filtering systems. The urgency for defenders is moderate, and organizations should schedule remediation as part of their patch management process.
Vulnerability Details
The official description of CVE-2021-27854 states that Layer 2 network filtering capabilities, such as IPv6 RA guard, can be bypassed using combinations of VLAN 0 headers, LLC/SNAP headers, and converting frames from Ethernet to Wi-Fi and its reverse. This vulnerability is classified as CWE-290, indicating a weakness related to Authentication Issues.
The CVSS score for this vulnerability is 4.7, which falls under the medium severity category. The attack vector is adjacent network, indicating that an attacker must be on the same local network to exploit this vulnerability. The attack complexity is low, and no privileges or user interaction are required to exploit it. The scope is changed, with a low impact on integrity but no impact on confidentiality or availability.
Technical Analysis
The root cause of this vulnerability lies in the network filtering mechanisms that are designed to prevent unauthorized network traffic. The ability to bypass these mechanisms using VLAN 0 headers and LLC/SNAP headers creates a significant security gap, allowing potential attackers to leverage this weakness for malicious purposes.
The attack vector for this vulnerability is classified as adjacent, meaning the attacker must have access to the same network segment as the target device. The complexity of the attack is low, indicating that minimal effort is required to exploit the vulnerability. No privileges are necessary, and user interaction is not required, making it easier for an attacker to exploit this vulnerability.
The impact on confidentiality is none, while the integrity impact is low. Availability remains unaffected, which means that while data integrity may be compromised, the system remains operational.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-27854 includes the potential for unauthorized access to network resources and data manipulation. This poses a significant risk to organizations that rely on Layer 2 filtering mechanisms for network security.
Organizations must recognize the importance of maintaining robust network security controls. The blast radius potential for this vulnerability is considerable, as it can affect multiple devices operating within the same network segment. Therefore, the urgency assessment is moderate, and organizations should schedule remediation in their patch management cycles.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions are affected by CVE-2021-27854: IEEE 802.2 up to 802.2h-1997 and IETF P802.1Q up to d1.0. Organizations should ensure that they update to the latest versions provided by the vendors to mitigate this vulnerability.
Mitigation & Remediation
To address this vulnerability, organizations should apply relevant patches and updates provided by the IEEE and IETF. If a patch is not available, consider implementing network segmentation to limit the exposure of vulnerable devices. Additionally, configuration hardening should be applied to network devices to strengthen their security posture.
Organizations are encouraged to perform thorough testing of their network security configurations and implement continuous monitoring solutions to detect any potential anomalies or unauthorized access attempts.
Detection Guidance
Organizations should monitor network traffic for any anomalies, particularly unusual patterns associated with VLAN manipulation or unexpected frame conversions. Logging indicators related to network security controls will also assist in identifying potential exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-27854 lies in the persistent challenge of maintaining effective Layer 2 security in increasingly complex network environments. This vulnerability underscores the necessity for organizations to continuously evaluate and enhance their network security protocols.
The pattern represented by this vulnerability highlights the importance of comprehensive testing and validation of network security measures. Organizations should learn from this incident and ensure that their security frameworks are resilient against similar vulnerabilities.
For further insights on improving network security, organizations may refer to our resources on network security architecture and leveraging the best practices in penetration testing methodology to strengthen their defenses.
Ultimately, organizations must remain vigilant and proactive in their approach to cybersecurity, adapting to the evolving threat landscape while ensuring robust protections against vulnerabilities such as CVE-2021-27854.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)