CVE-2021-30004 in wpa_supplicant
Summary
by MITRE • 04/02/2021
In wpa_supplicant and hostapd 2.9, forging attacks may occur because AlgorithmIdentifier parameters are mishandled in tls/pkcs1.c and tls/x509v3.c.
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Analysis
by VulDB Data Team • 04/07/2021
The vulnerability identified as CVE-2021-30004 affects wpa_supplicant and hostapd versions 2.9, where improper handling of AlgorithmIdentifier parameters in the TLS implementation creates opportunities for forging attacks. This flaw resides in the tls/pkcs1.c and tls/x509v3.c source files, which are critical components responsible for processing cryptographic algorithms and certificate validation within the wireless authentication framework. The issue stems from insufficient validation of cryptographic parameters during the processing of public key certificates, particularly when dealing with algorithm identifiers that define the cryptographic methods used for key operations.
The technical nature of this vulnerability aligns with CWE-295, which addresses improper certificate validation, and CWE-310, concerning cryptographic issues. Attackers can exploit this weakness by crafting malicious certificates that manipulate AlgorithmIdentifier parameters to bypass normal validation checks. This allows adversaries to perform man-in-the-middle attacks against wireless networks where wpa_supplicant or hostapd are in use, potentially gaining unauthorized access to network resources and compromising the integrity of wireless authentication processes. The flaw specifically impacts the certificate parsing and validation logic where the system fails to properly verify that the cryptographic parameters associated with AlgorithmIdentifier structures match expected values for the specified algorithms.
From an operational perspective, this vulnerability poses significant risks to wireless network security, particularly in enterprise environments where these components are commonly deployed for authentication purposes. The impact extends beyond simple authentication bypass to potentially enable full network compromise, as attackers can forge certificates that appear legitimate to the vulnerable systems. This creates a pathway for attackers to establish unauthorized connections to wireless networks, potentially leading to data exfiltration, network infiltration, and lateral movement within the compromised environment. The vulnerability affects both client devices using wpa_supplicant and access points using hostapd, making it particularly dangerous for wireless infrastructure deployments.
Mitigation strategies should focus on immediate patching of affected wpa_supplicant and hostapd installations to version 2.10 or later, which contain the necessary fixes for proper AlgorithmIdentifier parameter validation. Organizations should also implement additional monitoring for suspicious certificate validation patterns and consider deploying certificate transparency monitoring solutions to detect forged certificates. Network segmentation and additional authentication layers can provide defense-in-depth against potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1552.001, which covers credentials from password stores, as the compromised authentication system could lead to credential exposure, and T1046, network service scanning, as attackers might use the vulnerability to map and compromise wireless network infrastructure. Regular security assessments and vulnerability scanning should include checks for proper certificate handling in wireless authentication systems to prevent exploitation of similar cryptographic weaknesses.