CVE-2015-8764 in FreeRADIUS
Summary
by MITRE
Off-by-one error in the EAP-PWD module in FreeRADIUS 3.0 through 3.0.8, which triggers a buffer overflow.
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Analysis
by VulDB Data Team • 09/14/2020
The vulnerability identified as CVE-2015-8764 represents a critical buffer overflow condition within the EAP-PWD (Extensible Authentication Protocol - Password) module of FreeRADIUS versions 3.0 through 3.0.8. This flaw manifests as an off-by-one error that occurs during the processing of EAP-PWD authentication requests, creating a scenario where maliciously crafted authentication messages can cause the software to write beyond the bounds of allocated memory buffers. The issue specifically impacts the handling of password data during the EAP-PWD authentication exchange, which is commonly used in wireless network authentication scenarios and enterprise environments relying on radius-based authentication systems.
The technical implementation of this vulnerability stems from improper boundary checking within the EAP-PWD module's buffer management routines. When processing incoming EAP-PWD packets, the software fails to correctly validate the length of password data against the allocated buffer space, resulting in a single byte overflow that can corrupt adjacent memory regions. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation in authentication modules. The flaw is particularly dangerous because it occurs during the authentication process itself, potentially allowing attackers to exploit the buffer overflow to execute arbitrary code or cause denial of service conditions within the radius server environment.
The operational impact of CVE-2015-8764 extends beyond simple service disruption, as it creates potential attack vectors that align with several MITRE ATT&CK framework techniques including T1566 for credential access through network boundary exploitation and T1499 for network denial of service. Organizations utilizing FreeRADIUS for wireless network authentication, particularly those implementing WPA2-Enterprise or similar security frameworks, face significant risk from this vulnerability. The buffer overflow can be triggered by sending specially crafted EAP-PWD packets to a vulnerable FreeRADIUS server, potentially leading to complete system compromise if attackers can leverage the overflow to execute malicious code. Additionally, the vulnerability affects environments where EAP-PWD is used for authentication in wireless networks, VPN access, and other enterprise authentication scenarios that rely on radius servers for credential validation.
Mitigation strategies for CVE-2015-8764 require immediate patching of affected FreeRADIUS installations to versions 3.0.9 or later, which contain the necessary fixes for the buffer overflow condition. System administrators should also implement network monitoring to detect unusual EAP-PWD traffic patterns that might indicate exploitation attempts. Additional defensive measures include configuring network access controls to limit exposure of radius servers to untrusted networks, implementing intrusion detection systems that can identify malformed EAP packets, and conducting thorough network segmentation to contain potential exploitation impacts. Organizations should also review their authentication policies and consider implementing additional security layers such as certificate-based authentication or multi-factor authentication to reduce the attack surface. The vulnerability demonstrates the critical importance of proper input validation in authentication modules and highlights the need for regular security assessments of network infrastructure components that handle sensitive credential information.