CVE-2015-5316 in wpa_supplicant
Summary
by MITRE
The eap_pwd_perform_confirm_exchange function in eap_peer/eap_pwd.c in wpa_supplicant 2.x before 2.6, when EAP-pwd is enabled in a network configuration profile, allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via an EAP-pwd Confirm message followed by the Identity exchange.
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Analysis
by VulDB Data Team • 02/08/2023
The vulnerability identified as CVE-2015-5316 represents a critical denial of service flaw within the wpa_supplicant wireless authentication daemon. This issue specifically affects versions 2.x prior to 2.6 and occurs within the eap_pwd_perform_confirm_exchange function located in the eap_peer/eap_pwd.c file. The vulnerability manifests when EAP-pwd authentication is enabled in network configuration profiles, creating a scenario where remote attackers can exploit the protocol implementation to crash the daemon through carefully crafted EAP messages.
The technical flaw stems from improper input validation and state management within the EAP-pwd implementation. When a malicious attacker sends an EAP-pwd Confirm message followed by an Identity exchange, the function fails to properly handle the sequence of operations, leading to a NULL pointer dereference condition. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference issues in software implementations. The flaw occurs because the code does not adequately validate the state transitions or verify that required pointers are properly initialized before attempting to access them during the authentication process.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited by remote attackers without requiring any authentication credentials or privileged access. This makes it particularly dangerous in wireless network environments where attackers can potentially target authenticated clients or even the authentication server itself. The daemon crash resulting from this vulnerability can lead to complete network access disruption for affected clients, forcing them to reconnect to the wireless network and potentially creating temporary security gaps during reconnection processes. This type of attack aligns with ATT&CK technique T1499.001 which covers network denial of service attacks targeting wireless protocols.
The exploitation of this vulnerability demonstrates a classic state machine implementation flaw where the protocol handler does not properly account for all possible message sequences that can occur during EAP-pwd authentication. The attack vector requires the attacker to be within wireless range of the target device or to have access to the network to intercept and replay EAP messages, making it a significant concern for enterprise wireless deployments. Organizations using wpa_supplicant versions prior to 2.6 should prioritize immediate patching to prevent potential exploitation, as the vulnerability can be reliably triggered through standard network reconnaissance and attack tools. The fix implemented in wpa_supplicant 2.6 involves proper validation of pointer states and enhanced error handling during EAP-pwd message processing to prevent the NULL pointer dereference condition from occurring.