CVE-2015-5314 in Hostapd
Summary
by MITRE
The eap_pwd_process function in eap_server/eap_server_pwd.c in hostapd 2.x before 2.6 does not validate that the reassembly buffer is large enough for the final fragment when used with (1) an internal EAP server or (2) a RADIUS server and EAP-pwd is enabled in a runtime configuration, which allows remote attackers to cause a denial of service (process termination) via a large final fragment in an EAP-pwd message.
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Analysis
by VulDB Data Team • 02/08/2023
The vulnerability described in CVE-2015-5314 affects the hostapd wireless access point software version 2.x prior to 2.6, specifically within the eap_pwd_process function located in eap_server/eap_server_pwd.c. This flaw represents a classic buffer overflow condition that occurs during the processing of EAP-pwd (Extensible Authentication Protocol - Protected Wi-Fi) messages. The vulnerability manifests when the system attempts to reassemble fragmented EAP-pwd messages, particularly when handling the final fragment of a message sequence. The root cause lies in the absence of proper validation checks that would ensure the reassembly buffer has sufficient capacity to accommodate the final fragment data, regardless of whether the system operates as an internal EAP server or interfaces with a RADIUS server configured for EAP-pwd authentication.
The technical implementation of this vulnerability stems from inadequate input validation within the EAP-pwd processing pipeline. When an EAP-pwd message is transmitted in fragments, the hostapd server must reassemble these fragments into a complete message for proper processing. The flaw occurs during this reassembly phase where the system fails to verify that the allocated buffer space can accommodate the final fragment's data size. This condition creates a potential for memory corruption that can lead to process termination and subsequent denial of service. The vulnerability is particularly concerning because it can be exploited remotely through crafted EAP-pwd messages that contain oversized final fragments, making it applicable to both internal EAP server configurations and RADIUS server environments where EAP-pwd is enabled during runtime operations.
The operational impact of CVE-2015-5314 extends beyond simple service disruption to potentially compromise the entire wireless authentication infrastructure. When exploited successfully, this vulnerability allows remote attackers to cause process termination of the hostapd service, effectively rendering the wireless access point unable to authenticate users and provide network access. This denial of service condition can persist until the hostapd process is manually restarted or the system is rebooted, creating significant operational downtime for wireless networks. The vulnerability affects both internal EAP server deployments and RADIUS server configurations, making it particularly dangerous in enterprise environments where wireless authentication is critical for network access control. The remote exploitation capability means that attackers can target vulnerable systems without requiring physical access or network proximity, amplifying the security risk and potential impact on network availability.
Mitigation strategies for CVE-2015-5314 should focus on immediate software updates and configuration hardening measures. The primary and most effective remediation involves upgrading hostapd to version 2.6 or later, which includes the necessary buffer validation fixes for the EAP-pwd processing function. Organizations should also implement network monitoring to detect anomalous EAP-pwd message patterns that might indicate exploitation attempts. Additional defensive measures include configuring proper input validation on EAP-pwd message processing, implementing rate limiting for EAP authentication requests, and establishing robust intrusion detection systems that can identify malformed EAP-pwd fragments. From a cybersecurity framework perspective, this vulnerability aligns with CWE-129, which addresses insufficient size checks, and maps to ATT&CK technique T1190 for exploitation of remote services. Network administrators should also consider implementing network segmentation to limit the attack surface and ensure that wireless authentication services are properly isolated from critical network infrastructure to minimize the potential impact of such vulnerabilities.