CVE-2018-7034 in TEW-751DR
Summary
by MITRE
TRENDnet TEW-751DR v1.03B03, TEW-752DRU v1.03B01, and TEW733GR v1.03B01 devices allow authentication bypass via an AUTHORIZED_GROUP=1 value, as demonstrated by a request for getcfg.php.
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Analysis
by VulDB Data Team • 01/05/2020
The TRENDnet TEW-751DR, TEW-752DRU, and TEW733GR wireless routers represent a critical authentication bypass vulnerability that undermines the fundamental security posture of these network devices. These routers, which are widely deployed in residential and small office environments, suffer from a flaw in their web-based management interface that allows unauthenticated access to administrative functions through a specific parameter manipulation technique. The vulnerability manifests when an attacker sends a crafted request to the getcfg.php endpoint with the AUTHORIZED_GROUP=1 parameter, effectively circumventing the normal authentication process required to access router configuration settings.
This authentication bypass vulnerability stems from improper input validation and authorization checking within the router's web server implementation. The affected devices utilize a web interface that fails to properly validate the authorization status of incoming requests, particularly when processing the AUTHORIZED_GROUP parameter. When this parameter is set to a value of 1, the system incorrectly assumes that the request is authenticated and authorized, regardless of whether the user has actually provided valid credentials. This flaw exists at the application layer where the router's web server processes HTTP requests and determines access permissions, making it a classic example of inadequate access control mechanisms that aligns with CWE-285, which addresses improper authorization in software systems.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it provides attackers with complete administrative control over the affected routers. Once authenticated through this bypass, an attacker can modify network settings, change administrator passwords, configure port forwarding rules, enable or disable security features, and potentially redirect traffic to malicious servers. The implications are particularly severe in residential environments where these routers often serve as the primary gateway to home networks, potentially allowing attackers to establish persistent backdoors, monitor network traffic, or use the compromised devices as launching points for further attacks against other networked systems. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the T1078 credential access category, where adversaries use valid accounts to maintain access to systems.
The technical nature of this flaw demonstrates a fundamental weakness in the router's session management and authentication flow. The getcfg.php script, which is responsible for retrieving configuration data from the router, does not properly validate whether the requesting user has legitimate administrative privileges before processing the request. This oversight allows attackers to exploit the parameter value without providing any credentials, effectively creating a backdoor into the device's management interface. The vulnerability affects multiple models within the TRENDnet product line, indicating a systemic issue in the firmware implementation rather than an isolated incident. Network administrators and security professionals should recognize this as a critical issue requiring immediate remediation, as the attack surface is minimal and the impact is maximal, with the vulnerability being easily exploitable through simple HTTP request manipulation techniques. The flaw represents a failure in the principle of least privilege and proper authorization checking, which are fundamental security requirements that align with industry standards and best practices for secure software development.