CVE-2019-9494 in hostapd
Summary
by MITRE
The implementations of SAE in hostapd and wpa_supplicant are vulnerable to side channel attacks as a result of observable timing differences and cache access patterns. An attacker may be able to gain leaked information from a side channel attack that can be used for full password recovery. Both hostapd with SAE support and wpa_supplicant with SAE support prior to and including version 2.7 are affected.
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Analysis
by VulDB Data Team • 08/29/2023
The vulnerability identified as CVE-2019-9494 represents a critical side channel attack surface within the Secure Access Extension (SAE) implementations found in hostapd and wpa_supplicant wireless authentication frameworks. This flaw resides in the cryptographic operations performed during the SAE handshake process, where timing variations and cache access patterns inadvertently reveal information about the underlying cryptographic computations. The vulnerability affects versions of these wireless access point and client software prior to and including version 2.7, making a significant portion of deployed wireless infrastructure susceptible to this sophisticated attack vector.
The technical implementation flaw stems from the lack of constant-time cryptographic operations during SAE key exchange computations. When processing SAE authentication messages, the software exhibits measurable timing differences and cache access patterns that correlate with the cryptographic operations being performed. These timing variations occur during the computation of hash functions and elliptic curve operations that are fundamental to the SAE protocol's security model. The observable timing differences allow attackers to perform statistical analysis and correlation attacks that can reconstruct the password being used for authentication. This vulnerability specifically impacts the Dragonfly handshake mechanism within SAE, which is designed to provide forward secrecy and resistance to offline dictionary attacks, but suffers from implementation weaknesses that expose it to side channel reconnaissance.
The operational impact of this vulnerability extends beyond simple password recovery, as it fundamentally undermines the security assumptions of the SAE protocol. An attacker positioned within the wireless network's coverage area can leverage this side channel to perform offline password cracking attacks against WPA3-secured networks. The attack requires only passive monitoring of the wireless traffic during authentication attempts, making it particularly dangerous for environments where wireless access points are configured with SAE. This vulnerability effectively nullifies the security benefits that SAE was designed to provide, including resistance to dictionary attacks and forward secrecy properties. The implications are severe for enterprise environments where WPA3 is deployed as a security control, as it renders the network vulnerable to password recovery attacks that could compromise network access and potentially lead to broader network infiltration.
Mitigation strategies for CVE-2019-9494 require immediate software updates to versions that address the timing and cache access pattern vulnerabilities within the SAE implementations. Organizations should prioritize updating both hostapd and wpa_supplicant components to versions that implement constant-time cryptographic operations and eliminate the observable timing variations. Additionally, network administrators should consider implementing additional security controls such as disabling SAE where possible and relying on alternative authentication methods until the software updates are deployed. The vulnerability aligns with CWE-310, which addresses cryptographic weaknesses related to timing attacks, and represents a specific implementation gap that could be addressed through proper adherence to the NIST SP 800-57 cryptographic standards. From an ATT&CK framework perspective, this vulnerability maps to technique T1566, specifically targeting wireless network protocols for credential access, and could be leveraged by adversaries to establish persistent access to wireless networks through password recovery attacks that bypass traditional authentication controls.