CVE-2019-20661 in RBR50
Summary
by MITRE
Certain NETGEAR devices are affected by stored XSS. This affects RBR50 before 2.3.5.30, RBS50 before 2.3.5.30, and RBK50 before 2.3.5.30.
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Analysis
by VulDB Data Team • 05/26/2024
The vulnerability identified as CVE-2019-20661 represents a critical stored cross-site scripting flaw affecting several NETGEAR wireless router models including the RBR50 RBS50 and RBK50 series. This vulnerability resides in the web-based administrative interface of these devices and allows authenticated attackers with access to the device configuration to inject malicious scripts that persist in the device's memory. The affected firmware versions prior to 2.3.5.30 demonstrate a fundamental failure in input validation and output sanitization within the web management interface. The flaw specifically manifests when user-supplied data is stored and later rendered without proper encoding or filtering, creating a persistent vector for malicious code execution. This vulnerability falls under CWE-79 which categorizes cross-site scripting flaws as weaknesses in web applications that allow attackers to inject client-side scripts into web pages viewed by other users. The stored nature of this vulnerability means that malicious scripts remain embedded in the device's configuration and will execute every time the affected web interface is accessed by any user with appropriate privileges.
The operational impact of this vulnerability extends beyond simple script injection as it creates a persistent backdoor for attackers to execute arbitrary commands on the affected network devices. An attacker who gains access to the device's administrative interface can inject malicious JavaScript that will execute whenever any legitimate user accesses the device's web management portal. This creates a sophisticated attack vector where the attacker can perform actions such as stealing session cookies, redirecting users to malicious sites, modifying device configuration settings, or even establishing persistent access to the network infrastructure. The vulnerability enables attackers to leverage the device's privileged position within the network to conduct further reconnaissance and potentially escalate their access to other network resources. The attack surface is particularly concerning given that these are wireless routers that typically serve as gateway devices for home and small office networks, making them prime targets for attackers seeking to establish persistent network access. From an adversary perspective this vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1566 for credential access through social engineering or compromised credentials.
Mitigation strategies for CVE-2019-20661 require immediate firmware updates to versions 2.3.5.30 or later where NETGEAR has addressed the input validation issues. Network administrators should prioritize updating these devices as they represent critical infrastructure components with elevated privileges within network environments. Beyond firmware updates organizations should implement network monitoring to detect potential exploitation attempts and establish network segmentation to limit the impact if exploitation occurs. The vulnerability highlights the importance of proper input validation and output encoding practices in web applications, particularly those handling user-supplied data in administrative interfaces. Organizations should conduct regular vulnerability assessments of their network infrastructure and implement security testing procedures to identify similar flaws in other network devices. The remediation process should also include user access reviews to ensure that administrative privileges are properly controlled and that only authorized personnel have access to device management interfaces. Additionally, network administrators should consider implementing web application firewalls or security monitoring solutions that can detect and block suspicious script injection attempts in real-time. The vulnerability serves as a reminder of the critical need for secure coding practices and proper security testing throughout the software development lifecycle, particularly for network infrastructure devices that serve as entry points to broader network environments.