CVE-2023-52160: Wpa_supplicant PEAP Authentication Bypass Vulnerability and Exploit Details

In this post, we will discuss a newly discovered security vulnerability in the implementation of Protected Extensible Authentication Protocol (PEAP) within the wpa_supplicant software (versions 2.10 and earlier). An attacker could exploit this vulnerability to bypass authentication and gain unauthorized access to Enterprise Wi-Fi networks. We will go over the details of the vulnerability, reference the original research, and outline the steps for a successful attack.

CVE-2023-52160: WPA_Supplicant PEAP Authentication Bypass Vulnerability

The vulnerability in question, identified as CVE-2023-52160, exists within the implementation of PEAP authentication in the wpa_supplicant software. Specifically, it allows an attacker to bypass the Phase 2 authentication process when wpa_supplicant is configured to not verify the network's TLS certificate during Phase 1 authentication. This is achieved by exploiting an eap_peap_decrypt vulnerability, which enables the attacker to send an EAP-TLV Success packet and skip Phase 2 authentication.

For more information on this vulnerability, please refer to the original research and details published here.

Exploit Details

To better understand the exploit, let's first examine the PEAP authentication process, which consists of two phases:

1. Phase 1: Outer authentication - The client and server establish a secure TLS tunnel and exchange credentials.
2. Phase 2: Inner authentication - The client and server exchange encrypted authentication data inside the secure tunnel.

Configure wpa_supplicant to not verify the network's TLS certificate during Phase 1 authentication.

2. Abuse the eap_peap_decrypt vulnerability to send an EAP-TLV Success packet instead of starting Phase 2 authentication.

The following code snippet demonstrates how an attacker might send an EAP-TLV Success packet, leveraging the eap_peap_decrypt vulnerability:

// eap_peap.c

static void eap_peap_process(struct eap_peap_data *data,
                             struct eap_sm *sm,
                             struct eap_method_ret *ret,
                             const struct wpabuf *reqData,
                             struct wpabuf *respData)
{
    ...
    // Exploit the eap_peap_decrypt vulnerability
    send_eap_tlv_success(sm, respData);
    ...
}

The above code snippet illustrates how the attacker could take advantage of the eap_peap_decrypt vulnerability and modify the eap_peap_process function to send an EAP-TLV Success packet instead of initiating Phase 2 authentication.

With this exploit, an attacker could impersonate Enterprise Wi-Fi networks and potentially gain unauthorized access to sensitive information and network resources.

Conclusion

The CVE-2023-52160 vulnerability in wpa_supplicant's implementation of PEAP authentication poses a significant risk to the security of Enterprise Wi-Fi networks. By bypassing authentication and impersonating trusted networks, an attacker could gain unauthorized access to sensitive data and resources. It's crucial for organizations to ensure they are using the latest version of wpa_supplicant or have implemented appropriate mitigations (e.g., enabling TLS certificate validation) to protect against this vulnerability.

For more information on CVE-2023-52160 and the eap_peap_decrypt vulnerability, please refer to the original research and exploit details found here.

Timeline

Published on: 02/22/2024 17:15:08 UTC
Last modified on: 03/04/2024 22:47:18 UTC