CVE-2018-10561 in GPON Home Router
Summary
by MITRE
An issue was discovered on Dasan GPON home routers. It is possible to bypass authentication simply by appending "?images" to any URL of the device that requires authentication, as demonstrated by the /menu.html?images/ or /GponForm/diag_FORM?images/ URI. One can then manage the device.
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Analysis
by VulDB Data Team • 02/03/2025
This vulnerability exists in Dasan GPON home routers and represents a critical authentication bypass flaw that allows unauthorized access to administrative functions. The issue stems from improper access control implementation where the device fails to properly validate user credentials before granting access to protected administrative interfaces. The vulnerability manifests when attackers append the "?images" parameter to any authenticated URL, effectively circumventing the authentication mechanism entirely. This type of flaw falls under CWE-285 which specifically addresses improper authorization issues in software systems. The attack vector is particularly concerning because it requires no valid credentials or session tokens to gain administrative access to the router's management interface.
The technical implementation of this vulnerability demonstrates a fundamental flaw in the router's web application security architecture. When a user attempts to access any protected URI such as /menu.html?images or /GponForm/diag_FORM?images, the device should validate the user's authentication status before proceeding. However, the system incorrectly processes the "?images" parameter as a special access flag that bypasses authentication checks entirely. This creates a backdoor access path that allows any remote attacker to gain full administrative privileges without proper authentication. The vulnerability affects the router's web-based management interface and specifically targets the authentication logic implementation, making it a direct violation of secure coding practices.
The operational impact of this vulnerability is severe as it allows attackers to completely compromise the affected routers. Once authenticated, attackers can modify network configurations, change administrator passwords, install malicious firmware, or redirect traffic through the compromised device. This creates a persistent threat vector that can be exploited for various malicious activities including man-in-the-middle attacks, network monitoring, or as a pivot point for attacking other devices on the local network. The vulnerability affects all Dasan GPON home routers and can be exploited remotely without requiring physical access to the device. According to ATT&CK framework, this represents a privilege escalation technique using weak authentication mechanisms, specifically targeting the T1078 credential access tactic.
Mitigation strategies should include immediate firmware updates from Dasan to address the authentication bypass vulnerability. Network administrators should also implement network segmentation to limit the exposure of these devices to unauthorized users. The vulnerability can be addressed through proper access control implementation that validates authentication tokens before granting access to administrative functions. Additionally, network monitoring should be implemented to detect unusual access patterns to administrative interfaces. Organizations should also consider disabling unnecessary web management interfaces when not actively needed and implement strong network access controls to limit exposure. The fix should ensure that the web application properly validates all incoming requests and does not accept special parameters as authentication bypass mechanisms. This vulnerability highlights the importance of implementing proper input validation and access control checks in embedded web applications and demonstrates how seemingly simple flaws can lead to complete system compromise.