CVE-2021-27239 : Exploit Details and Defense Strategies
Learn about CVE-2021-27239, a critical vulnerability in NETGEAR R6400 and R6700 routers. Understand the impact, technical details, and mitigation steps to secure your network.
This CVE-2021-27239 article discusses a critical vulnerability affecting NETGEAR R6400 and R6700 routers. Attackers can exploit this flaw to execute arbitrary code without authentication via a crafted SSDP message, potentially leading to a stack-based buffer overflow.
Understanding CVE-2021-27239
This section delves into the impact, technical details, and mitigation strategies related to CVE-2021-27239.
What is CVE-2021-27239?
CVE-2021-27239 is a vulnerability in NETGEAR R6400 and R6700 routers' firmware version 1.0.4.98. Attackers can trigger a stack-based buffer overflow via the upnpd service, enabling them to execute code as root without authentication.
The Impact of CVE-2021-27239
The exploitation of CVE-2021-27239 could allow network-adjacent attackers to execute arbitrary code with high confidentiality, integrity, and availability impacts. The attack complexity is low, with no privileges required.
Technical Details of CVE-2021-27239
Let's explore the specific technical aspects of CVE-2021-27239 to understand its implications further.
Vulnerability Description
The vulnerability arises due to a stack-based buffer overflow triggered by a crafted MX header field in an SSDP message, allowing attackers to execute code in the context of root.
Affected Systems and Versions
NETGEAR R6400 and R6700 routers running firmware version 1.0.4.98 are impacted by this vulnerability.
Exploitation Mechanism
Attackers exploit the upnpd service listening on UDP port 1900 by sending a malicious SSDP message with a crafted MX header field, leading to a buffer overflow.
Mitigation and Prevention
Understanding how to mitigate and prevent CVE-2021-27239 is crucial to safeguard systems from potential attacks.
Immediate Steps to Take
Immediately update the firmware to the patched version provided by NETGEAR. Additionally, consider blocking external access to the affected routers until they are updated.
Long-Term Security Practices
Regularly update firmware, enable strong authentication mechanisms, and practice network segmentation to minimize the impact of future vulnerabilities.
Patching and Updates
Stay informed about security advisories from NETGEAR and apply patches promptly to maintain a secure network environment.