CVE-2019-20667 in RBR20
Summary
by MITRE
Certain NETGEAR devices are affected by stored XSS. This affects RBR20 before 2.3.5.26, RBS20 before 2.3.5.26, RBK20 before 2.3.5.26, RBR40 before 2.3.5.30, RBS40 before 2.3.5.30, RBK40 before 2.3.5.30, 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-2019-20667 represents a critical stored cross-site scripting flaw affecting multiple NETGEAR router models within the RBR, RBS, and RBK series. This security weakness allows attackers to inject malicious scripts into web applications that are then stored on the device and executed whenever users access the affected interfaces. The vulnerability impacts firmware versions prior to specific patches released by NETGEAR, with affected models including RBR20, RBS20, RBK20, RBR40, RBS40, RBK40, RBR50, RBS50, and RBK50, all running firmware versions below the mentioned patch levels. The stored XSS vulnerability occurs when user input is not properly sanitized before being processed and displayed within the web interface of these networking devices.
The technical exploitation of this vulnerability stems from inadequate input validation mechanisms within the web administration interfaces of these routers. When administrators or users enter data into web forms or configuration fields, the system fails to properly sanitize or escape special characters that could be interpreted as HTML or JavaScript code. This allows attackers to inject malicious scripts that persist in the device's memory and are subsequently executed whenever the vulnerable interface is accessed. The flaw operates at the application layer of the network stack, specifically within the web server component that manages device configuration and monitoring functions. This vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws, and represents a classic case of stored XSS where malicious payloads are permanently stored on the server rather than being reflected in a single request. The attack vector typically involves an authenticated user with administrative privileges or an attacker who can gain access to the device's web interface through other means.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to compromise the entire network infrastructure managed by these routers. Once a malicious script is injected, attackers can steal session cookies, redirect users to malicious websites, modify network configurations, or even execute arbitrary commands on the affected devices. The implications are particularly severe for enterprise environments where these routers serve as critical network gateways, as the compromise of a single device can lead to widespread network infiltration. The vulnerability also enables attackers to leverage the router's administrative privileges to modify firewall rules, DNS settings, or other network configurations that could facilitate further attacks or data exfiltration. This threat aligns with ATT&CK technique T1071.004 which covers application layer protocol: DNS, and T1059.007 which involves command and scripting interpreter: javascript, both of which can be facilitated through the exploitation of stored XSS vulnerabilities in network infrastructure devices.
Mitigation strategies for this vulnerability require immediate firmware updates from NETGEAR to address the specific XSS implementation flaws in the affected router models. Organizations should prioritize patching all affected devices regardless of their operational criticality, as the stored nature of the vulnerability means that once exploited, the malicious code persists until the device is updated or reset. Network administrators should also implement additional monitoring measures to detect unusual activity patterns that might indicate exploitation attempts, particularly around web interface access logs and configuration changes. The implementation of web application firewalls and input validation controls can provide additional defense in depth, while regular security assessments of network infrastructure should include testing for similar vulnerabilities in other network devices. Organizations should also consider network segmentation strategies to limit the potential impact of any successful exploitation, ensuring that even if a router is compromised, the attacker's access remains limited to the specific network segment controlled by that device. The vulnerability demonstrates the critical importance of proper input sanitization and output encoding in network device web interfaces, as well as the necessity of regular security updates and vulnerability assessments for all network infrastructure components.