CVE-2019-9974 in H660RM
Summary
by MITRE
diag_tool.cgi on DASAN H660RM GPON routers with firmware 1.03-0022 lacks any authorization check, which allows remote attackers to run a ping command via a GET request to enumerate LAN devices or crash the router with a DoS attack.
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Analysis
by VulDB Data Team • 05/24/2020
The CVE-2019-9974 vulnerability affects DASAN H660RM GPON routers running firmware version 1.03-0022, presenting a critical security flaw in the diag_tool.cgi web interface component. This vulnerability represents a classic authorization bypass issue that fundamentally undermines the router's security posture by allowing unauthenticated remote attackers to execute arbitrary commands on the device. The flaw exists within the diagnostic tool interface which should require proper authentication but instead accepts and processes commands without any verification of user credentials or privileges.
The technical implementation of this vulnerability stems from inadequate input validation and access control mechanisms within the diag_tool.cgi script. When a remote attacker sends a GET request containing command parameters to the vulnerable endpoint, the system processes these requests without performing any authorization checks. This design flaw enables attackers to leverage the ping command functionality to enumerate devices within the local network, effectively bypassing the router's network segmentation capabilities. The vulnerability's severity is amplified by the fact that it allows for both reconnaissance activities and denial of service conditions, making it particularly dangerous for network infrastructure.
From an operational impact perspective, this vulnerability creates significant risks for network administrators and end users who rely on these routers for home or small office connectivity. Attackers can exploit this weakness to discover internal network topology, identify connected devices, and potentially escalate their attacks through network reconnaissance. The ability to crash the router through denial of service attacks can result in complete network disruption, affecting internet connectivity for all devices connected to the affected network. This vulnerability particularly impacts environments where these routers are deployed without proper network segmentation or additional security controls, making them prime targets for automated exploitation campaigns.
The vulnerability aligns with CWE-284 (Improper Access Control) and maps to several ATT&CK techniques including T1046 (Network Service Scanning) and T1499 (Endpoint Denial of Service) within the adversary tactics framework. Organizations should implement immediate mitigations including firmware updates from the vendor, network segmentation to isolate affected devices, and firewall rules to block access to the vulnerable diag_tool.cgi endpoint from untrusted networks. Additionally, network monitoring should be enhanced to detect suspicious GET requests targeting the diagnostic interface, and regular security assessments should be conducted to identify similar authorization bypass vulnerabilities in other network equipment components. The incident underscores the critical importance of proper authentication mechanisms in network device management interfaces and demonstrates how seemingly minor access control oversights can lead to significant security breaches.