CVE-2021-45671 in CBR40
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by stored XSS. This affects CBR40 before 2.5.0.10, EAX80 before 1.0.1.62, EX7500 before 1.0.0.72, R7900 before 1.0.4.38, R8000 before 1.0.4.68, RAX200 before 1.0.4.120, RBS40V before 2.6.1.4, RBW30 before 2.6.1.4, MR60 before 1.0.6.110, RAX20 before 1.0.2.82, RAX45 before 1.0.2.72, RAX80 before 1.0.4.120, MS60 before 1.0.6.110, RAX15 before 1.0.2.82, RAX50 before 1.0.2.72, RAX75 before 1.0.4.120, RBR750 before 3.2.16.6, RBR850 before 3.2.16.6, RBS750 before 3.2.16.6, RBS850 before 3.2.16.6, RBK752 before 3.2.16.6, and RBK852 before 3.2.16.6.
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Analysis
by VulDB Data Team • 12/30/2021
The vulnerability CVE-2021-45671 represents a critical stored cross-site scripting flaw affecting numerous NETGEAR networking devices, including routers, access points, and wireless bridges. This vulnerability resides in the web-based management interfaces of affected devices, allowing attackers to inject malicious scripts that persist in the device's storage and execute when legitimate users access the administration panels. The flaw specifically impacts firmware versions prior to the listed patch releases, indicating that the vulnerability has existed for several years and affected a broad range of consumer and small office networking equipment. The stored nature of this XSS vulnerability means that once exploited, malicious code remains embedded in the device's configuration or web interface, making it particularly dangerous as it can affect multiple users who access the same compromised management interface. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws, and aligns with ATT&CK technique T1059.005 for command and scripting interpreter, as attackers can leverage the stored scripts to execute arbitrary commands on the device. The impact extends beyond simple script execution since these are networking devices that often serve as gateways to internal networks, potentially allowing attackers to gain unauthorized access to connected systems or manipulate network traffic.
The technical implementation of this stored XSS vulnerability involves the failure to properly sanitize user input in web forms or configuration parameters within the device's web interface. When users enter data into fields such as device names, SSID settings, or other configurable parameters, the device fails to adequately validate or escape special characters that could be interpreted as HTML or JavaScript code. Attackers can exploit this by injecting malicious payloads into these input fields during device configuration or while managing existing settings. The persistence of these scripts means that even after the initial injection, the malicious code continues to execute whenever the web interface is accessed, potentially affecting both administrators and regular users who might view the device's configuration pages. The vulnerability affects a diverse range of NETGEAR products including the R7900, R8000, RAX200, and various RBS, RBR, and RBK series devices, indicating a widespread issue across multiple product lines and firmware versions. This broad impact suggests that the vulnerability stems from a fundamental flaw in the web interface implementation rather than isolated coding errors, making it particularly concerning for network administrators managing multiple affected devices.
The operational impact of CVE-2021-45671 extends far beyond simple web interface compromise, as these networking devices often serve as critical infrastructure components within home and small office networks. When compromised, attackers can manipulate device settings, redirect traffic, or even establish persistent backdoors within the network. The stored nature of the vulnerability means that even if a device is rebooted, the malicious scripts remain active, potentially allowing attackers to maintain long-term access to the network infrastructure. Network administrators who access these devices for legitimate management purposes become unwitting participants in the attack, as their browsers execute the stored malicious code when they view the compromised web interface. This vulnerability can enable attackers to perform man-in-the-middle attacks, redirect users to malicious sites, or harvest credentials from users who might enter login information into compromised interfaces. The potential for lateral movement within networks increases significantly since these devices often serve as network gateways, and compromise of the management interface could provide attackers with insights into network topology and potentially access to internal systems. Additionally, the vulnerability may allow attackers to modify device firmware settings or configuration parameters, potentially leading to network disruption or complete compromise of network security controls. Organizations with multiple affected devices face the challenge of identifying and patching each vulnerable unit, as the vulnerability affects numerous product variants across different firmware versions, requiring careful inventory management and coordinated remediation efforts.
Mitigation strategies for CVE-2021-45671 must focus on immediate firmware updates from NETGEAR, as the vendor has released patches addressing this specific vulnerability. Network administrators should prioritize updating all affected devices to the latest firmware versions, particularly those listed in the vulnerability description, ensuring that all network infrastructure components are properly patched. System administrators should also implement network monitoring to detect potential exploitation attempts, including unusual traffic patterns or unauthorized configuration changes. The implementation of network segmentation can help limit the impact if devices are compromised, preventing lateral movement within the network. Additionally, organizations should consider disabling web-based management interfaces when not actively needed, as this reduces the attack surface and limits potential exploitation opportunities. Regular security audits of network infrastructure should include verification of device firmware versions and configuration settings to ensure that no affected devices remain unpatched. Security awareness training for network administrators can help them recognize potential exploitation indicators and understand the importance of maintaining current firmware versions. The vulnerability also highlights the importance of secure configuration practices, including the implementation of strong authentication mechanisms and regular review of device access controls. Organizations should establish procedures for tracking and managing device firmware updates across their entire network infrastructure to prevent similar vulnerabilities from remaining unpatched for extended periods. The remediation process should include thorough testing of updated firmware to ensure that device functionality remains intact while addressing the security vulnerability.