CVE-2022-23088 - FreeBSD Wi-Fi Remote Code Execution Vulnerability due to Improper IEEE 802.11s Mesh ID Length Validation

A critical vulnerability has been discovered in the FreeBSD operating system, specifically affecting the wireless networking subsystem. The vulnerability, designated as CVE-2022-23088, can lead to remote code execution, providing attackers unauthorized access, and potentially allowing them to take control of the affected system. This blog post aims to discuss the technical details of the vulnerability, demonstrate how exploitation can occur, and provide links to the relevant original references.

Background

FreeBSD is an open-source UNIX-like operating system, widely used in various applications, including web servers, embedded systems, and networking infrastructure.

This vulnerability is related to the handling of 802.11 beacon frames in the FreeBSD wireless networking subsystem. Beacon frames are used in Wi-Fi networks to announce the presence of a wireless network and provide information about its configuration. These frames are regularly transmitted by access points (APs) to inform potential clients about the available networks and their characteristics.

The vulnerability specifically affects the handling of IEEE 802.11s Mesh IDs. Mesh networking is an alternative network topology that allows for wireless devices to connect directly to one another without a central access point. IEEE 802.11s is the standard that defines the operations and management of wireless mesh networks.

Vulnerability Description

The vulnerability in CVE-2022-23088 lies in an incorrect validation of the length of an IEEE 802.11s Mesh ID before copying it into a heap-allocated buffer. By sending a specially crafted beacon frame with an improperly defined Mesh ID length, it is possible to trigger a buffer overflow, potentially leading to remote code execution.

The improper validation of the Mesh ID length within the 802.11 beacon handling routine could allow an attacker to overwrite kernel memory, affecting the system's stability and potentially allowing remote code execution. The vulnerability is particularly dangerous when a FreeBSD Wi-Fi client is in scanning mode (i.e., not associated with a specific SSID), as it is at this point that a malicious beacon frame may be able to exploit the vulnerability.

Exploit Details

In order to exploit this vulnerability (CVE-2022-23088), an attacker would need to be within the range of a vulnerable FreeBSD Wi-Fi client and send a malicious 802.11 beacon frame with an incorrect Mesh ID length. Here's an example of a code snippet that could be used to create a malicious beacon frame:

#include <stdint.h>
#include <string.h>

// ...

void create_malicious_beacon(uint8_t* buf, size_t buf_len) {
    // ...
    // Fill in the appropriate 802.11 header fields, such as
    // frame control, duration, addresses, etc.
    // ...
    
    // Add the Mesh ID information element (IE) with an incorrect length:
    uint8_t mesh_id_ie_len = xFF; // Incorrect length
    uint8_t mesh_id_ie_type = x7F; // Mesh ID IE type
    
    memcpy(buf, &mesh_id_ie_type, 1);
    memcpy(buf + 1, &mesh_id_ie_len, 1);

    // Fill in the remainder of the frame payload
    // (with arbitrary data, or a ROP chain to perform code execution)
    // ...
}

The above code snippet demonstrates how an attacker could create a malicious beacon frame with an incorrect Mesh ID length, potentially leading to a buffer overflow and remote code execution.

Remediation and Original References

As of the time of writing, patches have been released for FreeBSD to address this vulnerability. It is recommended that users and administrators using the affected FreeBSD versions update their systems as soon as possible to ensure they are protected from potential exploits.

For more information, please refer to the original references linked below

- FreeBSD Advisory
- CVE-2022-23088

Conclusion

In summary, the CVE-2022-23088 vulnerability in FreeBSD results from an improper validation of the length of an IEEE 802.11s Mesh ID within the 802.11 beacon handling routine. A successful exploit can lead to remote code execution, potentially allowing an attacker to take control of the affected system. By understanding the technical details of the vulnerability and updating systems with the available patches, users and administrators can better protect their FreeBSD installations and overall network infrastructure.

Timeline

Published on: 02/15/2024 05:15:09 UTC
Last modified on: 08/01/2024 13:42:36 UTC