CVE-2018-9248 in VDSL2 Modem HG 150-UB
Summary
by MITRE
FiberHome VDSL2 Modem HG 150-UB devices allow authentication bypass via a "Cookie: Name=0admin" header.
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Analysis
by VulDB Data Team • 08/31/2024
The FiberHome HG 150-UB VDSL2 modem represents a common consumer-grade networking device that connects households to internet service providers through digital subscriber line technology. These devices typically expose web-based management interfaces to allow users to configure network settings, monitor connection status, and manage security parameters. The vulnerability in question affects the authentication mechanism of the device's web interface, creating a critical security flaw that could be exploited by unauthorized users to gain administrative access without proper credentials. This particular vulnerability stems from a hardcoded authentication bypass mechanism within the device's software implementation.
The technical flaw manifests through a specific HTTP header manipulation vulnerability where the device accepts a predefined cookie value "Cookie: Name=0admin" as valid authentication credentials. This represents a classic implementation error where the system fails to properly validate user credentials and instead relies on a hardcoded value that bypasses normal authentication procedures. The vulnerability essentially allows any remote attacker to authenticate as an administrator by simply including this specific cookie header in their HTTP requests to the device's management interface. This type of flaw aligns with CWE-287 which addresses improper authentication issues and represents a fundamental failure in the device's security architecture.
The operational impact of this vulnerability is severe and far-reaching for affected users. An attacker who can reach the device's management interface can gain full administrative control over the modem, potentially allowing them to modify network configurations, disable security features, redirect traffic, or establish persistent access points. This access could enable man-in-the-middle attacks, DNS hijacking, or even serve as a stepping stone for further attacks within the local network. The vulnerability affects not just individual devices but potentially entire networks since the modem often serves as a gateway for all local traffic. According to ATT&CK framework, this represents a privilege escalation technique under T1068 and could facilitate lateral movement within the network.
Mitigation strategies for this vulnerability require immediate action from device owners and network administrators. The most effective immediate solution involves updating the device firmware to a version that addresses the hardcoded authentication bypass issue. However, many consumers may not be aware of available updates or may not have access to the manufacturer's support channels. Network administrators should implement network segmentation to isolate these devices from critical systems and consider disabling web management interfaces when not actively required. Additionally, implementing network monitoring to detect unusual authentication patterns or unauthorized access attempts can help identify exploitation attempts. Organizations should also consider deploying web application firewalls or implementing strict access controls that limit which IP addresses can reach the device's management interface. The vulnerability highlights the importance of secure coding practices and proper authentication implementation in embedded systems, emphasizing that devices connected to production networks require regular security assessments and updates to maintain their security posture.