CVE-2020-35829 in D7800
Summary
by MITRE • 12/30/2020
Certain NETGEAR devices are affected by stored XSS. This affects D7800 before 1.0.1.56, R7800 before 1.0.2.74, R8900 before 1.0.4.28, R9000 before 1.0.4.28, RAX120 before 1.0.0.78, RBK20 before 2.3.5.26, RBR20 before 2.3.5.26, RBS20 before 2.3.5.26, RBK40 before 2.3.5.30, RBR40 before 2.3.5.30, RBS40 before 2.3.5.30, RBK50 before 2.3.5.30, RBR50 before 2.3.5.30, RBS50 before 2.3.5.30, XR500 before 2.3.2.56, and XR700 before 1.0.1.10.
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Analysis
by VulDB Data Team • 12/30/2020
This vulnerability represents a critical stored cross-site scripting flaw that affects multiple NETGEAR router models across various product lines including the D7800, R7800, R8900, R9000, and several RAX, RBK, RBR, RBS, and XR series devices. The vulnerability stems from inadequate input validation and output encoding mechanisms within the affected firmware versions, allowing malicious actors to inject persistent malicious scripts into the device's web interface. When legitimate users access the compromised administrative interface, these stored scripts execute in their browser context, potentially compromising the entire network infrastructure.
The technical implementation of this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws where untrusted data is improperly sanitized before being rendered back to users. The flaw manifests when user-supplied input through web forms or configuration parameters is stored without proper sanitization and subsequently reflected in subsequent HTTP responses without adequate encoding. This creates a persistent vector where malicious code can be executed each time an authenticated user accesses the affected interface, making it particularly dangerous for network administrators who regularly interact with these devices.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with complete control over the affected routers' administrative interfaces. Attackers can leverage this access to modify network configurations, redirect traffic through malicious proxies, steal authentication credentials, or establish persistent backdoors within the network infrastructure. The widespread nature of affected models means that organizations deploying multiple NETGEAR devices across their networks face significant exposure risks, particularly in environments where network administrators maintain regular administrative access to these devices.
Mitigation strategies should prioritize immediate firmware updates to versions that address the stored XSS vulnerability, with particular attention to the specific version numbers mentioned in the advisory. Network segmentation and monitoring of administrative access attempts can provide additional layers of defense, while implementing strict access controls and multi-factor authentication for router administration interfaces helps minimize potential damage from successful exploitation attempts. Organizations should also consider network-based intrusion detection systems to monitor for suspicious traffic patterns that may indicate exploitation attempts, particularly focusing on unusual HTTP request patterns targeting the affected devices' web interfaces. The vulnerability demonstrates the critical importance of maintaining up-to-date firmware in enterprise environments and aligns with ATT&CK technique T1071.004 for application layer protocol usage, specifically targeting web protocols to achieve unauthorized access to network infrastructure components.