CVE-2019-11234 in FreeRADIUS
Summary
by MITRE
FreeRADIUS before 3.0.19 does not prevent use of reflection for authentication spoofing, aka a "Dragonblood" issue, a similar issue to CVE-2019-9497.
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Analysis
by VulDB Data Team • 06/01/2020
FreeRADIUS version 3.0.18 and earlier contains a critical authentication spoofing vulnerability that allows attackers to exploit reflection mechanisms within the RADIUS protocol implementation. This vulnerability specifically affects the authentication handling process where the server fails to properly validate or sanitize incoming authentication requests, enabling malicious actors to craft specially crafted packets that can be reflected back to the original sender. The flaw creates a condition where an attacker can manipulate the authentication flow by exploiting how the system processes and responds to authentication messages, potentially leading to unauthorized access or impersonation attacks. This vulnerability is categorized under CWE-284 Access Control and aligns with ATT&CK technique T1110.003 Credential Stuffing, as it enables attackers to bypass authentication controls through reflection-based manipulation.
The technical implementation of this vulnerability stems from insufficient input validation within the RADIUS authentication module. When FreeRADIUS processes authentication requests, it does not adequately verify the integrity of the authentication data or ensure that the response messages are properly associated with the correct authentication context. This allows an attacker to send a forged authentication request that appears to originate from a legitimate client, while the server's reflection mechanism inadvertently processes and responds to this request in a way that can be exploited for privilege escalation. The vulnerability is particularly concerning because it operates at the protocol level, affecting the fundamental authentication mechanism that FreeRADIUS uses to verify user credentials. The reflection aspect of the attack means that the system's own response mechanisms can be manipulated to provide attacker-controlled authentication responses.
The operational impact of CVE-2019-11234 is significant for organizations relying on FreeRADIUS for network access control, wireless authentication, or VPN services. Attackers exploiting this vulnerability could potentially gain unauthorized network access, escalate privileges, or perform man-in-the-middle attacks against legitimate users. The vulnerability affects enterprise networks, wireless infrastructure, and any systems where FreeRADIUS serves as the primary authentication server. Organizations using FreeRADIUS for authentication in sensitive environments may face data breaches, unauthorized system access, and potential compromise of network infrastructure. The attack vector requires minimal privileges and can be executed remotely, making it particularly dangerous for organizations with exposed RADIUS servers. This vulnerability also impacts compliance with security standards such as NIST 800-53 and ISO 27001, as it creates potential audit findings related to authentication controls and access management.
Organizations should immediately upgrade to FreeRADIUS version 3.0.19 or later, which includes patches specifically addressing the reflection vulnerability. Additional mitigations include implementing network segmentation to limit exposure of RADIUS servers, configuring proper access controls on the RADIUS server, and monitoring for unusual authentication patterns that might indicate exploitation attempts. Security teams should also consider implementing network-based intrusion detection systems that can identify and alert on suspicious RADIUS traffic patterns. The vulnerability highlights the importance of proper input validation and authentication integrity checking in network protocol implementations, as outlined in industry best practices such as those specified in the OWASP Top Ten and NIST Special Publication 800-63. Organizations should conduct comprehensive vulnerability assessments to ensure that all FreeRADIUS installations are properly updated and that network access controls are appropriately configured to prevent exploitation of this and similar authentication bypass vulnerabilities.