CVE-2019-9495 in hostapd
Summary
by MITRE
The implementations of EAP-PWD in hostapd and wpa_supplicant are vulnerable to side-channel attacks as a result of cache access patterns. All versions of hostapd and wpa_supplicant with EAP-PWD support are vulnerable. The ability to install and execute applications is necessary for a successful attack. Memory access patterns are visible in a shared cache. Weak passwords may be cracked. Versions of hostapd/wpa_supplicant 2.7 and newer, are not vulnerable to the timing attack described in CVE-2019-9494. Both hostapd with EAP-pwd support and wpa_supplicant with EAP-pwd support prior to and including version 2.7 are affected.
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Analysis
by VulDB Data Team • 08/29/2023
The vulnerability described in CVE-2019-9495 represents a significant side-channel attack surface within the enterprise authentication frameworks of hostapd and wpa_supplicant. This weakness specifically targets the EAP-PWD (Extensible Authentication Protocol - Password) implementation, which is designed to provide secure password-based authentication for wireless networks. The flaw stems from observable cache access patterns during cryptographic operations, creating a pathway for attackers to infer sensitive information through indirect means. The vulnerability affects all versions of these wireless authentication daemons that support EAP-PWD functionality, making it particularly concerning for organizations relying on wireless infrastructure security.
The technical implementation of EAP-PWD in these systems creates predictable memory access patterns that leak information through shared cache structures. When cryptographic operations process password credentials, the cache behavior reveals timing information that can be exploited by attackers. This cache timing side-channel vulnerability operates under the principles of cache timing attacks, where variations in cache access times correlate with cryptographic operations. The attack requires local access to install and execute malicious applications, meaning an attacker must already have a foothold within the network environment. This prerequisite significantly reduces the attack surface but does not eliminate the risk, particularly in environments where privilege escalation or insider threats exist.
The operational impact of this vulnerability extends beyond simple credential theft, as it specifically targets password-based authentication mechanisms that many organizations still rely upon for wireless access control. Weak passwords become particularly vulnerable to exploitation since the side-channel attack can accelerate the process of password cracking by revealing information about the password structure through cache access patterns. The vulnerability affects both hostapd and wpa_supplicant implementations, creating a widespread risk across wireless infrastructure deployments. Organizations using these tools for EAP-PWD authentication face potential unauthorized access to wireless networks, which could lead to broader network compromise and data exfiltration.
Security mitigations for this vulnerability focus on addressing the cache timing side-channel through implementation hardening and code optimization. The recommended approach involves updating to versions 2.7 and newer of both hostapd and wpa_supplicant, which have implemented countermeasures against the specific cache timing attack patterns. These updates typically incorporate constant-time cryptographic implementations that eliminate the predictable memory access patterns. Organizations should also consider implementing additional authentication layers and monitoring for suspicious cache access patterns. The vulnerability aligns with CWE-310 (Cryptographic Implementation Fault) and represents a specific instance of cache timing attacks that fall under ATT&CK technique T1059.007 (Command and Scripting Interpreter: PowerShell) when attackers leverage local access to deploy exploitation tools, though the primary attack vector remains cache timing rather than direct command execution.