CVE-2025-3674 in A3700R
Summary
by MITRE • 04/16/2025
A vulnerability was found in TOTOLINK A3700R 9.1.2u.5822_B20200513. It has been declared as critical. Affected by this vulnerability is the function setUrlFilterRules of the file /cgi-bin/cstecgi.cgi. The manipulation leads to improper access controls. The attack can be launched remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 04/16/2025
The vulnerability identified as CVE-2025-3674 represents a critical access control flaw in the TOTOLINK A3700R router firmware version 9.1.2u.5822_B20200513. This issue resides within the setUrlFilterRules function of the /cgi-bin/cstecgi.cgi file, which serves as a core component for managing web content filtering policies on the device. The vulnerability has been publicly disclosed and is considered exploitable, posing significant security risks to affected networks. The flaw allows unauthorized manipulation of URL filtering rules through remote exploitation, bypassing the intended access controls that should protect administrative functions.
The technical nature of this vulnerability stems from improper access control implementation within the router's web interface management system. When the setUrlFilterRules function processes incoming requests through the cgi-bin interface, it fails to properly validate user authentication credentials or authorization levels. This weakness enables attackers to craft malicious requests that can modify URL filtering policies without proper administrative privileges. The vulnerability specifically affects the authentication mechanisms that should prevent unauthorized users from accessing or modifying critical router configuration parameters. According to CWE classification, this represents a weakness in access control mechanisms, specifically CWE-284 which addresses improper access control in software systems.
The operational impact of CVE-2025-3674 extends beyond simple unauthorized access to encompass potential network compromise and data interception capabilities. An attacker who successfully exploits this vulnerability can modify URL filtering rules to allow access to malicious websites, block legitimate services, or redirect traffic through compromised endpoints. This capability provides attackers with persistent access to the network and enables various attack vectors including man-in-the-middle scenarios, credential theft, and malware distribution. The remote exploitability of this vulnerability means that attackers do not require physical access to the device or network presence within the local network, making the attack surface significantly broader.
Security professionals should recognize this vulnerability as a critical threat that aligns with ATT&CK technique T1071.004 for application layer protocol: DNS and T1566.001 for credential harvesting through social engineering. The exposure of administrative functions through the cgi-bin interface creates opportunities for attackers to escalate privileges and establish persistent network footholds. Organizations using affected TOTOLINK A3700R devices should immediately implement network segmentation to isolate these devices from critical systems and establish monitoring for unauthorized configuration changes. The vulnerability demonstrates the importance of proper input validation and authentication checks in web-based administrative interfaces, as outlined in OWASP Top 10 2021 category A07: Identification and Authentication Failures.
Mitigation strategies should include immediate firmware updates from TOTOLINK if available, network access control implementation through firewall rules that restrict access to the cgi-bin interface, and comprehensive network monitoring for suspicious configuration changes. Security teams should also conduct thorough network audits to identify any unauthorized modifications that may have occurred since the vulnerability disclosure. The exploitability of this vulnerability through public disclosure means that attackers can readily develop automated tools to target affected devices, emphasizing the urgency of remediation efforts. Organizations should implement network behavior monitoring to detect anomalous access patterns to administrative interfaces and establish incident response procedures specifically addressing router configuration compromise scenarios.