CVE-2018-15702 in TL-WRN841N
Summary
by MITRE
The web interface in TP-Link TL-WRN841N 0.9.1 4.16 v0348.0 is vulnerable to CSRF due to insufficient validation of the referer field.
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Analysis
by VulDB Data Team • 03/28/2020
The TP-Link TL-WRN841N router model running firmware version 0.9.1 4.16 v0348.0 presents a significant cross-site request forgery vulnerability that compromises the device's administrative security. This vulnerability stems from the web interface's inadequate validation mechanisms for the referer field, which is a critical security control that should verify the origin of incoming requests to prevent unauthorized administrative actions. The flaw allows attackers to execute malicious requests on behalf of authenticated users without their knowledge or consent, effectively bypassing the authentication mechanisms that should protect the device's configuration interface.
The technical implementation of this vulnerability demonstrates a classic CSRF weakness where the web application fails to properly validate the referer header or implement proper anti-CSRF tokens. When an authenticated user visits a malicious website or clicks on a crafted link, the attacker can construct requests that will be executed by the user's browser against the vulnerable router's web interface. This occurs because the application relies solely on the referer field for validation, which can be easily manipulated or omitted by attackers. The vulnerability is particularly concerning as it affects the router's administrative interface, which controls critical network configuration settings including firewall rules, wireless network parameters, and user access controls. The absence of robust CSRF protection mechanisms means that an attacker can perform administrative actions such as changing the wireless password, modifying network settings, or even resetting the device to factory defaults without the legitimate user's awareness or authorization.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it can lead to complete network compromise and persistent backdoor access. An attacker who successfully exploits this vulnerability can establish long-term control over the network infrastructure by modifying the router's configuration to redirect traffic through malicious servers or by creating persistent access points. The vulnerability affects the device's ability to maintain secure network boundaries, potentially allowing lateral movement within the network and access to sensitive internal systems. The specific firmware version mentioned indicates this is likely a widespread issue affecting multiple devices in the TL-WRN841N product line, making it a significant concern for organizations and individuals who rely on these devices for network security. This vulnerability aligns with CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses, and represents a critical gap in the application's security controls that violates fundamental web security principles.
Mitigation strategies for this vulnerability should prioritize immediate firmware updates from TP-Link to address the CSRF validation issues. Organizations should implement network segmentation and access controls to limit exposure of these devices to untrusted networks. The implementation of proper anti-CSRF tokens and robust referer header validation should be enforced across all web interfaces to prevent similar vulnerabilities. Network monitoring should be enhanced to detect unusual configuration changes that might indicate exploitation attempts. Additionally, users should be educated about the risks of visiting untrusted websites while authenticated to administrative interfaces, and the use of dedicated management networks separate from user-facing networks should be considered. This vulnerability demonstrates the importance of implementing defense-in-depth strategies and proper security controls in network infrastructure devices, as highlighted by ATT&CK technique T1071.004 for application layer protocol usage and T1566 for credential access through social engineering approaches that leverage CSRF weaknesses.