CVE-2020-24374 in Freebox HD
Summary
by MITRE
A DNS rebinding vulnerability in Freebox HD before 1.5.29.
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Analysis
by VulDB Data Team • 09/17/2020
The DNS rebinding vulnerability identified as CVE-2020-24374 affects Freebox HD devices running firmware versions prior to 1.5.29, representing a critical security flaw that allows attackers to bypass network isolation mechanisms and gain unauthorized access to internal network resources. This vulnerability specifically targets the device's DNS resolution behavior and demonstrates how improper handling of DNS responses can be exploited to undermine network security boundaries. The flaw enables attackers to manipulate DNS queries in a way that allows them to redirect traffic to internal network addresses that would normally be inaccessible from external networks, effectively breaking down the firewall protections that typically separate internal and external network zones.
The technical implementation of this vulnerability stems from the device's failure to properly validate DNS responses and maintain consistent hostname resolution behavior across different network contexts. When a malicious actor crafts specific DNS responses that appear legitimate to the Freebox HD device, the system can be tricked into resolving internal network addresses that are typically protected by network segmentation. This occurs because the device does not adequately verify the consistency of DNS responses or implement proper validation mechanisms that would prevent such cross-zone redirection attacks. The vulnerability falls under CWE-611, which specifically addresses improper access control in web applications and network services, and aligns with ATT&CK technique T1133 where adversaries use DNS tunneling and manipulation to bypass network controls.
The operational impact of this vulnerability extends beyond simple network access bypass, as it provides attackers with the capability to perform reconnaissance activities, escalate privileges, and potentially gain full control over the affected device and its connected network resources. Attackers can leverage this vulnerability to access internal services, web interfaces, and other networked devices that would normally be protected by the device's firewall configuration. The implications are particularly severe for home and small office networks where Freebox HD devices serve as primary gateways, as these systems often contain sensitive personal data and may be connected to critical infrastructure components. The vulnerability also enables potential lateral movement within networks, as attackers can use the compromised device as a pivot point to access other systems that are not directly exposed to the internet.
Mitigation strategies for CVE-2020-24374 require immediate firmware updates to version 1.5.29 or later, which contain patches specifically designed to address the DNS rebinding behavior. Network administrators should also implement additional protective measures including DNS filtering mechanisms, network segmentation policies, and monitoring for suspicious DNS query patterns. The device configuration should be reviewed to ensure that unnecessary services are disabled and that proper access controls are implemented. Organizations should also consider implementing DNS security extensions to provide additional validation and integrity checking for DNS responses. According to industry best practices and security frameworks, this vulnerability highlights the importance of implementing robust input validation and consistent network behavior policies, particularly in network gateway and firewall devices that serve as critical security boundaries within enterprise and home networks.