CVE-2004-0938 in FreeRADIUS
Summary
by MITRE
FreeRADIUS before 1.0.1 allows remote attackers to cause a denial of service (server crash) by sending an Ascend-Send-Secret attribute without the required leading packet.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/16/2024
The vulnerability described in CVE-2004-0938 represents a critical denial of service flaw affecting FreeRADIUS versions prior to 1.0.1. This issue specifically targets the RADIUS protocol implementation within the FreeRADIUS server software, which is widely deployed for network access control and authentication services. The vulnerability manifests when the server receives a malformed Ascend-Send-Secret attribute that lacks the required leading packet structure, causing the service to crash and become unavailable to legitimate users. This flaw directly impacts the availability aspect of the CIA triad, potentially disrupting network authentication services across organizations that depend on FreeRADIUS for access control.
The technical root cause of this vulnerability stems from inadequate input validation within the RADIUS packet processing logic. When FreeRADIUS encounters an Ascend-Send-Secret attribute, it expects a specific packet format that includes a leading packet header. Without this required structure, the server fails to properly handle the attribute and subsequently crashes. This represents a classic buffer over-read or improper state handling vulnerability that falls under CWE-129, which covers issues related to insufficient validation of the length of input data. The flaw demonstrates poor error handling practices where the system does not gracefully manage malformed input rather than attempting to recover or reject the invalid data.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers to systematically degrade network authentication services. Network administrators who rely on FreeRADIUS for wireless network access, VPN connections, or other authentication services face significant risk from this flaw. The vulnerability can be exploited through network-based attacks where an attacker sends specially crafted RADIUS packets to the target server, potentially leading to extended outages that affect multiple users and services. This type of attack aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and specifically targets the availability of network services.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to FreeRADIUS version 1.0.1 or later, which contains the necessary patches to properly handle malformed Ascend-Send-Secret attributes. Network segmentation and access control measures can provide additional protection by limiting exposure to potentially malicious traffic. Monitoring systems should be configured to detect unusual RADIUS packet patterns that might indicate exploitation attempts, and incident response procedures should be updated to address potential service disruption scenarios. The vulnerability highlights the importance of proper input validation and error handling in network services, particularly those handling authentication and access control functions. Security teams should also consider implementing rate limiting and packet filtering rules to prevent exploitation while waiting for official patches to be deployed across all affected systems.